diff --git a/docs/Reduced_Operator_Kernel_build.md b/docs/Reduced_Operator_Kernel_build.md
index 7c6413284b..02e761e5c6 100644
--- a/docs/Reduced_Operator_Kernel_build.md
+++ b/docs/Reduced_Operator_Kernel_build.md
@@ -2,13 +2,13 @@
 
 In order to reduce the compiled binary size of ONNX Runtime (ORT), the operator kernels included in the build can be reduced to just the kernels required by your model/s.
 
-A configuration file must be created with details of the kernels that are required. 
+A configuration file must be created with details of the kernels that are required.
 
-Following that, ORT must be manually built, providing the configuration file in the `--include_ops_by_config` parameter. The build process will update the ORT kernel registration source files to exclude the unused kernels. 
+Following that, ORT must be manually built, providing the configuration file in the `--include_ops_by_config` parameter. The build process will update the ORT kernel registration source files to exclude the unused kernels.
 
 See the [build instructions](https://www.onnxruntime.ai/docs/how-to/build.html#build-instructions) for more details on building ORT.
 
-When building ORT with a reduced set of kernel registrations, `--skip_tests` **MUST** be specified as the kernel reduction will render many of the unit tests invalid. 
+When building ORT with a reduced set of kernel registrations, `--skip_tests` **MUST** be specified as the kernel reduction will render many of the unit tests invalid.
 
 NOTE: The operator exclusion logic when building with an operator reduction configuration file will only disable kernel registrations each time it runs. It will NOT re-enable previously disabled kernels. If you wish to change the list of kernels included, it is best to revert the repository to a clean state (e.g. via `git reset --hard`) before building ORT again.
 
@@ -75,7 +75,7 @@ If, for example, the types of inputs 0 and 1 were important, the entry may look
   `{"inputs": {"0": ["float", "int32_t"], "1": ["int32_t"]}}`
 
 Finally some operators do non-standard things and store their type information under a 'custom' key.
-ai.onnx.OneHot is an example of this, where 3 type names from the inputs are combined into a string.
-  `{"custom": ["float_int64_t_int64_t", "int64_t_string_int64_t"]}`
+ai.onnx.OneHot is an example of this, where the three input types are combined into a triple.
+  `{"custom": [["float", "int64_t", "int64_t"], ["int64_t", "std::string", "int64_t"]]}`
 
-For these reasons, it is best to generate the configuration file first, and manually edit any entries if needed. 
+For these reasons, it is best to generate the configuration file first, and manually edit any entries if needed.
diff --git a/tools/ci_build/github/azure-pipelines/linux-cpu-minimal-build-ci-pipeline.yml b/tools/ci_build/github/azure-pipelines/linux-cpu-minimal-build-ci-pipeline.yml
index 7fe6b69152..9b45ad9e04 100644
--- a/tools/ci_build/github/azure-pipelines/linux-cpu-minimal-build-ci-pipeline.yml
+++ b/tools/ci_build/github/azure-pipelines/linux-cpu-minimal-build-ci-pipeline.yml
@@ -130,7 +130,9 @@ jobs:
     displayName: Build minimal onnxruntime [exceptions ENABLED, type reduction ENABLED (globally allowed types)] and run tests
     inputs:
       script: |
-        echo "!globally_allowed_types;bool,float,int8_t,uint8_t" \
+        printf "%s\n%s\n" \
+          "!globally_allowed_types;bool,float,int8_t,uint8_t" \
+          "!no_ops_specified_means_all_ops_are_required" \
           > $(test_data_directory)/globally_allowed_types.config && \
         docker run --rm \
           --volume $(Build.SourcesDirectory):/onnxruntime_src \
diff --git a/tools/ci_build/op_registration_utils.py b/tools/ci_build/op_registration_utils.py
index 7de949340c..7ea776d00c 100644
--- a/tools/ci_build/op_registration_utils.py
+++ b/tools/ci_build/op_registration_utils.py
@@ -184,6 +184,11 @@ def _process_lines(lines: typing.List[str], offset: int, registration_processor:
         registration_processor.process_registration(lines_to_process, domain, op_type,
                                                     int(start_version), int(end_version), type)
 
+    else:
+        log.warning("Ignoring unhandled kernel registration variant: {}".format(code_line))
+        for line in lines_to_process:
+            registration_processor.process_other_line(line)
+
     return offset + 1
 
 
diff --git a/tools/ci_build/reduce_op_kernels.py b/tools/ci_build/reduce_op_kernels.py
index 8387a541b8..427bb77f7b 100755
--- a/tools/ci_build/reduce_op_kernels.py
+++ b/tools/ci_build/reduce_op_kernels.py
@@ -5,7 +5,6 @@
 import argparse
 import op_registration_utils
 import os
-import re
 import shutil
 import sys
 import typing
@@ -19,74 +18,24 @@ ort_tools_py_path = os.path.abspath(os.path.join(ort_root, 'tools', 'python'))
 sys.path.append(ort_tools_py_path)
 
 from util import parse_config  # noqa
-from util.ort_format_model.operator_type_usage_processors import OperatorTypeUsageManager  # noqa
+from util.ort_format_model.operator_type_usage_processors import OpTypeImplFilterInterface  # noqa
 
 log = get_logger("reduce_op_kernels")
 
 
-# valid C++ scalar types that can be specified as globally allowed types
-_valid_allowed_types = {
-    "bool",
-    "uint8_t", "uint16_t", "uint32_t", "uint64_t",
-    "int8_t", "int16_t", "int32_t", "int64_t",
-    "MLFloat16", "BFloat16",  # in onnxruntime namespace
-    "float", "double",
-    "string",  # in std namespace
-}
-
-
-def _validated_globally_allowed_types(globally_allowed_types: typing.Collection[str]) -> typing.Set[str]:
-    '''Return a valid set of globally allowed types.'''
-    # ensure globally_allowed_types is a set
-    if not isinstance(globally_allowed_types, set):
-        globally_allowed_types = set(globally_allowed_types)
-
-    if not globally_allowed_types <= _valid_allowed_types:
-        raise ValueError(
-            "Globally allowed types must be a subset of valid allowed types. Actual: {}, valid: {}".format(
-                globally_allowed_types, sorted(_valid_allowed_types)))
-
-    return globally_allowed_types
-
-
-def _type_re_from_globally_allowed_types(globally_allowed_types: typing.Set[str]) -> typing.re.Pattern:
-    '''Return a regular expression to match type registration strings to a set of globally allowed types.'''
-    # to keep a registration, the type should match patterns like:
-    # 1. T0
-    # 2. T0_T1_T2
-    # where Ti is a member of globally_allowed_types and multiple Ti's are delimited by "_"
-    # this covers both the common case (1) and special cases like OneHot registration (2)
-    allowed_type_subpattern = \
-        "(?:" + "|".join(re.escape(allowed_type) for allowed_type in sorted(globally_allowed_types)) + ")"
-    return re.compile("^{0}(?:_{0})*$".format(allowed_type_subpattern))
-
-
 class _ExcludingRegistrationProcessor(op_registration_utils.RegistrationProcessor):
     '''Registration processor that excludes registrations and writes the result to an output file.'''
-    def __init__(self, required_ops: dict, op_type_usage_manager: typing.Optional[OperatorTypeUsageManager],
-                 globally_allowed_types: typing.Optional[typing.Set[str]], output_file: str):
+    def __init__(self, required_ops: typing.Optional[dict],
+                 op_type_impl_filter: typing.Optional[OpTypeImplFilterInterface],
+                 output_file: str):
         self._required_ops = required_ops
-
-        if op_type_usage_manager is not None and globally_allowed_types is not None:
-            raise ValueError("At most one of op_type_usage_manager and globally_allowed_types may be provided.")
-
-        self._op_type_usage_manager = op_type_usage_manager
-
-        self._enable_all_ops = globally_allowed_types is not None and not required_ops
-        if self._enable_all_ops:
-            log.info("No required ops were specified but globally allowed types were specified. "
-                     "Globally allowed types will be used to exclude op implementations.")
-
-        self._globally_allowed_types_re = \
-            _type_re_from_globally_allowed_types(globally_allowed_types) \
-            if globally_allowed_types is not None else None
-
+        self._op_type_impl_filter = op_type_impl_filter
         self._output_file = output_file
 
     def _is_op_required(self, domain: str, operator: str,
                         start_version: int, end_version: typing.Optional[int]) -> typing.Tuple[bool, str]:
-        '''See if an op should be excluded because it is not required.'''
-        if self._enable_all_ops:
+        '''See if an op is required.'''
+        if self._required_ops is None:
             return True
 
         if domain not in self._required_ops:
@@ -116,17 +65,10 @@ class _ExcludingRegistrationProcessor(op_registration_utils.RegistrationProcesso
                 exclude = True
                 reason = "Entire op is not required."
 
-            if not exclude and type is not None:
-                if self._op_type_usage_manager is not None:
-                    if not self._op_type_usage_manager.is_typed_registration_needed(domain, operator, type):
-                        exclude = True
-                        reason = "Specific typed registration is not required."
-
-                elif self._globally_allowed_types_re is not None:
-                    if not self._globally_allowed_types_re.match(type):
-                        exclude = True
-                        reason = "Specific typed registration does not contain globally allowed types."
-
+            if not exclude and type is not None and self._op_type_impl_filter is not None:
+                if not self._op_type_impl_filter.is_typed_registration_needed(domain, operator, type):
+                    exclude = True
+                    reason = "Specific typed registration is not required."
         else:
             log.warning('Keeping {} registration from unknown domain: {}'
                         .format(registration_identifier, constant_for_domain))
@@ -152,9 +94,8 @@ class _ExcludingRegistrationProcessor(op_registration_utils.RegistrationProcesso
 
 def _process_provider_registrations(
         ort_root: str, use_cuda: bool,
-        required_ops: dict,
-        op_type_usage_manager: typing.Optional[OperatorTypeUsageManager],
-        globally_allowed_types: typing.Optional[typing.Set[str]]):
+        required_ops: typing.Optional[dict],
+        op_type_impl_filter: typing.Optional[OpTypeImplFilterInterface]):
     '''Rewrite provider registration files.'''
     kernel_registration_files = op_registration_utils.get_kernel_registration_files(ort_root, use_cuda)
 
@@ -169,8 +110,7 @@ def _process_provider_registrations(
 
         # read from backup and overwrite original with commented out lines for any kernels that are not required
         with open(kernel_registration_file, 'w') as file_to_write:
-            processor = _ExcludingRegistrationProcessor(
-                required_ops, op_type_usage_manager, globally_allowed_types, file_to_write)
+            processor = _ExcludingRegistrationProcessor(required_ops, op_type_impl_filter, file_to_write)
 
             op_registration_utils.process_kernel_registration_file(backup_path, processor)
 
@@ -231,20 +171,11 @@ def reduce_ops(config_path: str, enable_type_reduction: bool = False, use_cuda:
     :param enable_type_reduction: Whether per operator type reduction is enabled
     :param use_cuda: Whether to reduce op kernels for the CUDA provider
     '''
-    required_ops, op_type_usage_manager, globally_allowed_types = parse_config(config_path, enable_type_reduction)
+    required_ops, op_type_impl_filter = parse_config(config_path, enable_type_reduction)
 
-    if globally_allowed_types is not None:
-        globally_allowed_types = _validated_globally_allowed_types(globally_allowed_types)
+    _process_provider_registrations(ort_root, use_cuda, required_ops, op_type_impl_filter)
 
-    _process_provider_registrations(ort_root, use_cuda, required_ops, op_type_usage_manager, globally_allowed_types)
-
-    if op_type_usage_manager is not None:
-        type_control_cpp_code = op_type_usage_manager.get_cpp_entries()
-    elif globally_allowed_types is not None:
-        type_control_cpp_code = ["ORT_SPECIFY_OP_KERNEL_GLOBAL_ALLOWED_TYPES({});".format(
-            ", ".join(sorted(globally_allowed_types)))]
-    else:
-        type_control_cpp_code = []
+    type_control_cpp_code = op_type_impl_filter.get_cpp_entries() if op_type_impl_filter is not None else []
 
     _insert_type_control_cpp_code(ort_root, type_control_cpp_code)
 
diff --git a/tools/python/util/ort_format_model/__init__.py b/tools/python/util/ort_format_model/__init__.py
index e5ec840d42..5ee341c5f0 100644
--- a/tools/python/util/ort_format_model/__init__.py
+++ b/tools/python/util/ort_format_model/__init__.py
@@ -12,4 +12,7 @@ sys.path.append(ort_fbs_py_path)
 
 from .utils import create_config_from_models  # noqa
 from .ort_model_processor import OrtFormatModelProcessor  # noqa
-from .operator_type_usage_processors import OperatorTypeUsageManager  # noqa
+from .operator_type_usage_processors import (  # noqa
+    GloballyAllowedTypesOpTypeImplFilter,
+    OpTypeImplFilterInterface,
+    OperatorTypeUsageManager)
diff --git a/tools/python/util/ort_format_model/operator_type_usage_processors.py b/tools/python/util/ort_format_model/operator_type_usage_processors.py
index ff9b6d7c3c..6d2b5c84a6 100644
--- a/tools/python/util/ort_format_model/operator_type_usage_processors.py
+++ b/tools/python/util/ort_format_model/operator_type_usage_processors.py
@@ -2,10 +2,11 @@
 # Licensed under the MIT License.
 
 import json
+import typing
 import ort_flatbuffers_py.experimental.fbs as fbs
 
 from abc import ABC, abstractmethod
-from .types import value_name_to_typestr
+from .types import FbsTypeInfo, value_name_to_typestr
 
 
 def _create_op_key(domain: str, optype: str):
@@ -31,6 +32,26 @@ def _ort_constant_for_domain(domain: str):
     return domain_to_constant_map[domain]
 
 
+def _reg_type_to_cpp_type(reg_type: str):
+    if reg_type == "string":
+        return "std::string"
+    return reg_type
+
+
+def _split_reg_types(reg_types_str: str):
+    '''
+    Split on underscores but append "_t" to the previous element.
+    '''
+    tokens = reg_types_str.split("_")
+    reg_types = []
+    for token in tokens:
+        if token == "t" and len(reg_types) > 0:
+            reg_types[-1] += "_t"
+        else:
+            reg_types += [token]
+    return reg_types
+
+
 class TypeUsageProcessor(ABC):
     '''
     Abstract base class for processors which implement operator specific logic to determine the type or types required.
@@ -44,22 +65,25 @@ class TypeUsageProcessor(ABC):
     def process_node(self, node: fbs.Node, value_name_to_typeinfo: dict):
         pass
 
-    def is_typed_registration_needed(self, type_in_registration):
+    def is_typed_registration_needed(self, type_in_registration: str,
+                                     globally_allowed_types: typing.Optional[typing.Set[str]]):
         '''
         Given the string from a kernel registration, determine if the registration is required or not.
         :param type_in_registration: Type string from kernel registration
+        :param globally_allowed_types: Optional set of globally allowed types. If provided, these types take precedence
+                                       in determining the required types.
         :return: True is required. False if not.
         '''
         # Not all operators have typed registrations, so this is optionally implemented by derived classes
         raise RuntimeError('Did not expect processor for {} to have typed registrations.'.format(self.name))
 
-    @abstractmethod
     def get_cpp_entry(self):
         '''
         Get the C++ code that specifies this operator's required types.
         :return: List with any applicable C++ code for this operator's required types. One line per entry.
         '''
-        pass
+        # Not applicable for some ops, so return no lines by default.
+        return []
 
     @abstractmethod
     def to_config_entry(self):
@@ -84,14 +108,23 @@ class DefaultTypeUsageProcessor(TypeUsageProcessor):
     Operator processor which tracks the types used for selected input/s and/or output/s.
     '''
 
-    def __init__(self, domain: str, optype: str, inputs: [int] = [0], outputs: [int] = []):
+    def __init__(self, domain: str, optype: str, inputs: [int] = [0], outputs: [int] = [],
+                 required_input_types: typing.Dict[int, typing.Set[str]] = {},
+                 required_output_types: typing.Dict[int, typing.Set[str]] = {}):
         '''
         Create DefaultTypeUsageProcessor. Types for one or more inputs and/or outputs can be tracked by the processor.
         The default is to track the types required for input 0, as this is the most common use case in ONNX.
+
+        Required input and output types may be specified. These are only applicable to is_typed_registration_needed().
+        If a registration type matches a required type, the typed registration is needed.
+        There is a separate mechanism for specifying required types from C++ for kernels with untyped registration.
+
         :param domain: Operator domain.
         :param optype: Operator name.
         :param inputs: Inputs to track. Zero based index. May be empty.
         :param outputs: Outputs to track. Zero based index. May be empty.
+        :param required_input_types: Required input types. May be empty.
+        :param required_output_types: Required output types. May be empty.
         '''
         super().__init__(domain, optype)
         self._input_types = {}
@@ -106,6 +139,25 @@ class DefaultTypeUsageProcessor(TypeUsageProcessor):
         if not inputs and not outputs:
             raise ValueError('At least one input or output must be tracked')
 
+        self._required_input_types = required_input_types
+        self._required_output_types = required_output_types
+
+    def _is_type_enabled(self, reg_type, index, required_types, allowed_type_set):
+        cpp_type = _reg_type_to_cpp_type(reg_type)
+        return cpp_type in required_types.get(index, set()) or cpp_type in allowed_type_set
+
+    def is_input_type_enabled(self, reg_type, index, allowed_type_set=None):
+        '''Whether input type is enabled based on required and allowed types.'''
+        if allowed_type_set is None:
+            allowed_type_set = self._input_types[index]
+        return self._is_type_enabled(reg_type, index, self._required_input_types, allowed_type_set)
+
+    def is_output_type_enabled(self, reg_type, index, allowed_type_set=None):
+        '''Whether output type is enabled based on required and allowed types.'''
+        if allowed_type_set is None:
+            allowed_type_set = self._output_types[index]
+        return self._is_type_enabled(reg_type, index, self._required_output_types, allowed_type_set)
+
     def process_node(self, node: fbs.Node, value_name_to_typeinfo: dict):
         for i in self._input_types.keys():
             if i >= node.InputsLength():
@@ -128,13 +180,14 @@ class DefaultTypeUsageProcessor(TypeUsageProcessor):
             type_str = value_name_to_typestr(node.Outputs(o), value_name_to_typeinfo)
             self._output_types[o].add(type_str)
 
-    def is_typed_registration_needed(self, type_in_registration: str):
+    def is_typed_registration_needed(self, type_in_registration: str,
+                                     globally_allowed_types: typing.Optional[typing.Set[str]]):
         if 0 not in self._input_types.keys():
             # currently all standard typed registrations are for input 0.
             # custom registrations can be handled by operator specific processors (e.g. OneHotProcessor below).
             raise RuntimeError('Expected typed registration to use type from input 0. Node:{}'.format(self.name))
 
-        return type_in_registration in self._input_types[0]
+        return self.is_input_type_enabled(type_in_registration, 0, globally_allowed_types)
 
     def get_cpp_entry(self):
         entries = []
@@ -195,8 +248,9 @@ class Output0TypedRegistrationProcessor(DefaultTypeUsageProcessor):
         # init with tracking of output 0 only.
         super().__init__(domain, optype, inputs=[], outputs=[0])
 
-    def is_typed_registration_needed(self, type_in_registration: str):
-        return type_in_registration in self._output_types[0]
+    def is_typed_registration_needed(self, type_in_registration: str,
+                                     globally_allowed_types: typing.Optional[typing.Set[str]]):
+        return self.is_output_type_enabled(type_in_registration, 0, globally_allowed_types)
 
 
 class OneHotProcessor(TypeUsageProcessor):
@@ -212,18 +266,18 @@ class OneHotProcessor(TypeUsageProcessor):
         type0 = value_name_to_typestr(node.Inputs(0), value_name_to_typeinfo)
         type1 = value_name_to_typestr(node.Inputs(1), value_name_to_typeinfo)
         type2 = value_name_to_typestr(node.Inputs(2), value_name_to_typeinfo)
-        key = '{}_{}_{}'.format(type0, type1, type2)
+        # types in kernel registration are ordered this way: input (T1), output (T3), depth (T2)
+        key = (type0, type2, type1)
         self._triples.add(key)
 
-    def is_typed_registration_needed(self, type_in_registration):
-        # the OneHot registration involves a concatenation of the 3 types involved, in the format we match
-        # when adding values in process_node
-        return type_in_registration in self._triples
-
-    def get_cpp_entry(self):
-        # exclusion is via commenting out the registration entry, so don't need to write any #defines
-        # to disable type support for the OneHot operator
-        return None
+    def is_typed_registration_needed(self, type_in_registration: str,
+                                     globally_allowed_types: typing.Optional[typing.Set[str]]):
+        # the OneHot registration involves a concatenation of the 3 types involved
+        reg_types = tuple([_reg_type_to_cpp_type(reg_type) for reg_type in _split_reg_types(type_in_registration)])
+        if globally_allowed_types is not None:
+            return all(reg_type in globally_allowed_types for reg_type in reg_types)
+        else:
+            return reg_types in self._triples
 
     def to_config_entry(self):
         if not self._triples:
@@ -237,7 +291,7 @@ class OneHotProcessor(TypeUsageProcessor):
         self._triples.clear()
         aggregate_info = json.loads(entry)
         if 'custom' in aggregate_info:
-            self._triples = set(aggregate_info['custom'])
+            self._triples = set([tuple(triple) for triple in aggregate_info['custom']])
 
 
 def _create_operator_type_usage_processors():
@@ -267,25 +321,33 @@ def _create_operator_type_usage_processors():
     # - Implementation does not have any significant type specific code:
     #    ai.onnx: Concat, Flatten, Not, QLinearConv, Reshape, Shape, Squeeze, Unsqueeze
     #
-    default_processor_onnx_ops = ['Abs', 'Add', 'ArgMax', 'ArgMin', 'AveragePool',
+    default_processor_onnx_ops = ['Abs', 'ArgMax', 'ArgMin', 'AveragePool',
                                   'BatchNormalization', 'BitShift',
                                   'Ceil', 'Clip', 'Conv', 'CumSum',
-                                  'DequantizeLinear', 'Div',
-                                  'Equal', 'Exp', 'Expand',
+                                  'DequantizeLinear',
+                                  'Exp', 'Expand',
                                   'Floor',
-                                  'Gemm', 'Greater',
-                                  'IsNaN'
-                                  'Less', 'Log', 'LogSoftmax', 'LpNormalization',
-                                  'MatMul', 'Max', 'Min', 'Mul',
+                                  'Gemm',
+                                  'IsNaN',
+                                  'Log', 'LogSoftmax', 'LpNormalization',
+                                  'MatMul', 'Max', 'Min',
                                   'Neg', 'NonMaxSuppression', 'NonZero',
                                   'Pad',
                                   'Range', 'Reciprocal', 'ReduceL1', 'ReduceL2', 'ReduceLogSum', 'ReduceLogSumExp',
                                   'ReduceMax', 'ReduceMean', 'ReduceMin', 'ReduceProd', 'ReduceSum', 'ReduceSumSquare',
                                   'Relu', 'Resize', 'RoiAlign', 'Round',
-                                  'Sigmoid', 'Sin', 'Softmax', 'Split', 'Sqrt', 'Sub',
+                                  'Sigmoid', 'Sin', 'Softmax', 'Split', 'Sqrt',
                                   'Tanh', 'Tile', 'TopK', 'Transpose',
                                   'Where']
 
+    default_processor_onnx_ops_requiring_int64_for_input_0 = ['Add',
+                                                              'Div',
+                                                              'Equal',
+                                                              'Greater',
+                                                              'Less',
+                                                              'Mul',
+                                                              'Sub']
+
     internal_ops = ['QLinearAdd', 'QLinearMul']
 
     # TODO - review and add ML ops as needed
@@ -300,6 +362,8 @@ def _create_operator_type_usage_processors():
     default_processor_onnxml_ops = []
 
     [add(DefaultTypeUsageProcessor('ai.onnx', op)) for op in default_processor_onnx_ops]
+    [add(DefaultTypeUsageProcessor('ai.onnx', op, required_input_types={0: {"int64_t"}}))
+        for op in default_processor_onnx_ops_requiring_int64_for_input_0]
     [add(DefaultTypeUsageProcessor('ai.onnx.ml', op)) for op in default_processor_onnxml_ops]
     [add(DefaultTypeUsageProcessor('com.microsoft', op)) for op in internal_ops]
 
@@ -335,6 +399,30 @@ def _create_operator_type_usage_processors():
     return operator_processors
 
 
+class OpTypeImplFilterInterface(ABC):
+    '''
+    Class that filters operator implementations based on type.
+    '''
+    @abstractmethod
+    def is_typed_registration_needed(self, domain: str, optype: str, type_registration_str: str):
+        '''
+        Given the string from a kernel registration, determine if the registration is required or not.
+        :param domain: Operator domain.
+        :param optype: Operator type.
+        :param type_registration_str: Type string from kernel registration
+        :return: True is required. False if not.
+        '''
+        pass
+
+    @abstractmethod
+    def get_cpp_entries(self):
+        '''
+        Get the C++ code that specifies the operator types to enable.
+        :return: List of strings. One line of C++ code per entry.
+        '''
+        pass
+
+
 class OperatorTypeUsageManager:
     '''
     Class to manage the operator type usage processors.
@@ -371,32 +459,6 @@ class OperatorTypeUsageManager:
         if op_processor:
             op_processor.process_node(node, value_name_to_typeinfo)
 
-    def is_typed_registration_needed(self, domain: str, optype: str, type_registration_str: str):
-        '''
-        Given the string from a kernel registration, determine if the registration is required or not.
-        :param domain: Operator domain.
-        :param optype: Operator type.
-        :param type_registration_str: Type string from kernel registration
-        :return: True is required. False if not.
-        '''
-        needed = True  # we keep the registration unless the per-operator processor says not to
-        key = _create_op_key(domain, optype)
-        if key in self._operator_processors:
-            needed = self._operator_processors[key].is_typed_registration_needed(type_registration_str)
-
-        return needed
-
-    def get_cpp_entries(self):
-        '''
-        Get the C++ code that define the lists of types to enable for the operators we have type info for.
-        :return: List of strings. One line of C++ code per entry.
-        '''
-        entries = []
-        for key in sorted(self._operator_processors.keys()):
-            entries.extend(self._operator_processors[key].get_cpp_entry())
-
-        return entries
-
     def get_config_entry(self, domain: str, optype: str):
         '''
         Get the config entry specifying the types for this operator.
@@ -438,3 +500,61 @@ class OperatorTypeUsageManager:
                 # same values back
                 self._operator_processors[key].from_config_entry(entry)
                 assert(entry == self._operator_processors[key].to_config_entry())
+
+    class _OpTypeImplFilter(OpTypeImplFilterInterface):
+        def __init__(self, manager):
+            self._manager = manager
+
+        def is_typed_registration_needed(self, domain: str, optype: str, type_registration_str: str):
+            needed = True  # we keep the registration unless the per-operator processor says not to
+            key = _create_op_key(domain, optype)
+            if key in self._manager._operator_processors:
+                needed = self._manager._operator_processors[key].is_typed_registration_needed(
+                    type_in_registration=type_registration_str, globally_allowed_types=None)
+
+            return needed
+
+        def get_cpp_entries(self):
+            entries = []
+            for key in sorted(self._manager._operator_processors.keys()):
+                entries.extend(self._manager._operator_processors[key].get_cpp_entry())
+
+            return entries
+
+    def make_op_type_impl_filter(self):
+        '''
+        Creates an OpTypeImplFilterInterface instance from this manager.
+        Filtering uses the manager's operator type usage processor state.
+        '''
+        return OperatorTypeUsageManager._OpTypeImplFilter(self)
+
+
+class GloballyAllowedTypesOpTypeImplFilter(OpTypeImplFilterInterface):
+    '''
+    Operator implementation filter which uses globally allowed types.
+    '''
+    _valid_allowed_types = set(FbsTypeInfo.tensordatatype_to_string.values())
+
+    def __init__(self, globally_allowed_types: typing.Set[str]):
+        self._operator_processors = _create_operator_type_usage_processors()
+
+        if not globally_allowed_types.issubset(self._valid_allowed_types):
+            raise ValueError("Globally allowed types must all be valid. Invalid types: {}"
+                             .format(sorted(globally_allowed_types - self._valid_allowed_types)))
+
+        self._globally_allowed_types = globally_allowed_types
+
+    def is_typed_registration_needed(self, domain: str, optype: str, type_registration_str: str):
+        key = _create_op_key(domain, optype)
+        if key in self._operator_processors:
+            needed = self._operator_processors[key].is_typed_registration_needed(
+                type_in_registration=type_registration_str,
+                globally_allowed_types=self._globally_allowed_types)
+        else:
+            needed = _reg_type_to_cpp_type(type_registration_str) in self._globally_allowed_types
+
+        return needed
+
+    def get_cpp_entries(self):
+        return ["ORT_SPECIFY_OP_KERNEL_GLOBAL_ALLOWED_TYPES({});".format(
+            ", ".join(sorted(self._globally_allowed_types)))]
diff --git a/tools/python/util/ort_format_model/types.py b/tools/python/util/ort_format_model/types.py
index a2f69b3735..76e69615b4 100644
--- a/tools/python/util/ort_format_model/types.py
+++ b/tools/python/util/ort_format_model/types.py
@@ -20,8 +20,8 @@ class FbsTypeInfo:
         fbs.TensorDataType.TensorDataType.DOUBLE: 'double',
         fbs.TensorDataType.TensorDataType.UINT32: 'uint32_t',
         fbs.TensorDataType.TensorDataType.UINT64: 'uint64_t',
-        fbs.TensorDataType.TensorDataType.COMPLEX64: 'complex64 is not supported',
-        fbs.TensorDataType.TensorDataType.COMPLEX128: 'complex128 is not supported',
+        # fbs.TensorDataType.TensorDataType.COMPLEX64: 'complex64 is not supported',
+        # fbs.TensorDataType.TensorDataType.COMPLEX128: 'complex128 is not supported',
         fbs.TensorDataType.TensorDataType.BFLOAT16: 'BFloat16'
     }
 
diff --git a/tools/python/util/reduced_build_config_parser.py b/tools/python/util/reduced_build_config_parser.py
index f49ae637b2..420111ee01 100644
--- a/tools/python/util/reduced_build_config_parser.py
+++ b/tools/python/util/reduced_build_config_parser.py
@@ -7,21 +7,24 @@ import os
 try:
     import flatbuffers  # noqa
     have_flatbuffers = True
-    from .ort_format_model import OperatorTypeUsageManager  # noqa
+    from .ort_format_model import GloballyAllowedTypesOpTypeImplFilter, OperatorTypeUsageManager  # noqa
 except ImportError:
     have_flatbuffers = False
 
 
 def parse_config(config_file: str, enable_type_reduction: bool = False):
     '''
-    Parse the configuration file and return the required operators dictionary, and possibly either an
-    OperatorTypeUsageManager or a globally allowed types list.
+    Parse the configuration file and return the required operators dictionary and an
+    OpTypeImplFilterInterface instance.
 
     Configuration file lines can do the following:
     1. specify required operators
     2. specify globally allowed types for all operators
+    3. specify what it means for no required operators to be specified
 
-    The basic format for specifying required operators (1) is `domain;opset;op1,op2...`
+    1. Specifying required operators
+
+    The basic format for specifying required operators is `domain;opset;op1,op2...`
     e.g. `ai.onnx;11;Add,Cast,Clip,...
 
     If the configuration file is generated from ORT format models it may optionally contain JSON for per-operator
@@ -41,50 +44,72 @@ def parse_config(config_file: str, enable_type_reduction: bool = False):
         `{"inputs": {"0": ["float", "int32_t"], "1": ["int32_t"]}}`
 
     Finally some operators do non-standard things and store their type information under a 'custom' key.
-    ai.onnx.OneHot is an example of this, where 3 type names from the inputs are combined into a string.
-        `{"custom": ["float_int64_t_int64_t", "int64_t_string_int64_t"]}`
+    ai.onnx.OneHot is an example of this, where the three input types are combined into a triple.
+        `{"custom": [["float", "int64_t", "int64_t"], ["int64_t", "std::string", "int64_t"]]}`
+
+    2. Specifying globally allowed types for all operators
+
+    The format for specifying globally allowed types for all operators is:
+        `!globally_allowed_types;T0,T1,...`
 
-    The format for specifying globally allowed types for all operators (2) is `!globally_allowed_types;T0,T1,...`
     Ti should be a C++ scalar type supported by ONNX and ORT.
     At most one globally allowed types specification is allowed.
 
     Specifying per-operator type information and specifying globally allowed types are mutually exclusive - it is an
     error to specify both.
 
+    3. Specify what it means for no required operators to be specified
+
+    By default, if no required operators are specified, NO operators are required.
+
+    With the following line, if no required operators are specified, ALL operators are required:
+        `!no_ops_specified_means_all_ops_are_required`
+
     :param config_file: Configuration file to parse
     :param enable_type_reduction: Set to True to use the type information in the config.
                                   If False the type information will be ignored.
-                                  If the flatbuffers module is unavailable op-specific type information will be ignored
-                                  as the per-op usage of the type information is via OperatorTypeUsageManager which has
-                                  a dependency on the ORT flatbuffers python schema.
-    :return: required_ops, op_type_usage_manager, globally_allowed_types:
-             Dictionary of domain:opset:[ops] for required operators
-             OperatorTypeUsageManager manager with operator specific type usage information if available. None if
-             type reduction was disabled, per-op type reduction was not specified, or the flatbuffers module is not
-             available.
-             List of globally allowed types. None if type reduction was disabled, or globally allowed types were not
-             specified.
-             At most one of the op_type_usage_manager and globally_allowed_types tuple elements will not be None.
+                                  If the flatbuffers module is unavailable type information will be ignored as the
+                                  type-based filtering has a dependency on the ORT flatbuffers schema.
+    :return: required_ops: Dictionary of domain:opset:[ops] for required operators. If None, all operators are
+                           required.
+             op_type_impl_filter: OpTypeImplFilterInterface instance if type reduction is enabled, the flatbuffers
+                                  module is available, and type reduction information is present. None otherwise.
     '''
 
     if not os.path.isfile(config_file):
         raise ValueError('Configuration file {} does not exist'.format(config_file))
 
+    # only enable type reduction when flatbuffers is available
+    enable_type_reduction = enable_type_reduction and have_flatbuffers
+
     required_ops = {}
-    op_type_usage_manager = OperatorTypeUsageManager() if enable_type_reduction and have_flatbuffers else None
+    no_ops_specified_means_all_ops_are_required = False
+    op_type_usage_manager = OperatorTypeUsageManager() if enable_type_reduction else None
     has_op_type_reduction_info = False
     globally_allowed_types = None
 
+    def process_non_op_line(line):
+        if not line or line.startswith("#"):  # skip empty lines and comments
+            return True
+
+        if line.startswith("!globally_allowed_types;"):  # handle globally allowed types
+            if enable_type_reduction:
+                nonlocal globally_allowed_types
+                if globally_allowed_types is not None:
+                    raise RuntimeError("Globally allowed types were already specified.")
+                globally_allowed_types = set(segment.strip() for segment in line.split(';')[1].split(','))
+            return True
+
+        if line == "!no_ops_specified_means_all_ops_are_required":  # handle all ops required line
+            nonlocal no_ops_specified_means_all_ops_are_required
+            no_ops_specified_means_all_ops_are_required = True
+            return True
+
+        return False
+
     with open(config_file, 'r') as config:
         for line in [orig_line.strip() for orig_line in config.readlines()]:
-            if not line or line.startswith("#"):  # skip empty lines and comments
-                continue
-
-            if line.startswith("!globally_allowed_types;"):  # handle globally allowed types
-                if enable_type_reduction:
-                    if globally_allowed_types is not None:
-                        raise RuntimeError("Globally allowed types were already specified.")
-                    globally_allowed_types = [segment.strip() for segment in line.split(';')[1].split(',')]
+            if process_non_op_line(line):
                 continue
 
             domain, opset_str, operators_str = [segment.strip() for segment in line.split(';')]
@@ -151,6 +176,10 @@ def parse_config(config_file: str, enable_type_reduction: bool = False):
             else:
                 required_ops[domain][opset].update(operators)
 
+    if len(required_ops) == 0 and no_ops_specified_means_all_ops_are_required:
+        required_ops = None
+
+    op_type_impl_filter = None
     if enable_type_reduction:
         if not has_op_type_reduction_info:
             op_type_usage_manager = None
@@ -158,4 +187,9 @@ def parse_config(config_file: str, enable_type_reduction: bool = False):
             raise RuntimeError(
                 "Specifying globally allowed types and per-op type reduction info together is unsupported.")
 
-    return required_ops, op_type_usage_manager, globally_allowed_types
+        if globally_allowed_types is not None:
+            op_type_impl_filter = GloballyAllowedTypesOpTypeImplFilter(globally_allowed_types)
+        elif op_type_usage_manager is not None:
+            op_type_impl_filter = op_type_usage_manager.make_op_type_impl_filter()
+
+    return required_ops, op_type_impl_filter