Named Entity Recognition 25.3
Named Entity Recognition User and Programming Guide

# Case Sensitive Matches

By default, Named Entity Recognition matches characters case sensitively, which has better performance than case insensitive matching. When you require case insensitive matching, there are several ways to configure it:

- configure `MatchCase`.

- configure individual grammars, entities, and entries with case sensitivity options, in a custom grammar file.

- use case normalization.

OpenText recommends that you always create and use Named Entity Recognition grammars that allow you to do case sensitive matching, because it has better performance. Most of the standard grammars come with entities using common and appropriate case styles. Some also have different entities for different case styles. If your data uses a consistent case, it is unlikely that you need to use case insensitive matching.

## Configure MatchCase

The simplest way to turn off case sensitivity is to set the `MatchCase` configuration parameter to `False` in the configuration file.

If you run Named Entity Recognition with `MatchCase=False`, entities are optimized for case-insensitive matching when they are loaded. This can increase the time required to initialize Named Entity Recognition, so if you regularly use a grammar file with `MatchCase=False` you can optimize the entities for case-insensitive matching at compile time instead. See Optimize Case-Insensitive Matching.

`MatchCase` applies to all matches, so it can have a significant performance impact. In general, OpenText recommends that you use one of the other options to enable case insensitive matching. For the best performance, write a grammar file using only upper or lower case and then normalize your input (see Case Normalization).

## Configure Custom Grammars

When you create your own custom XML grammar files, you can configure individual grammars, entities, and entries individually to be case sensitive or insensitive.

When you configure case sensitivity at a lower level, it overrides the higher level settings. Additionally, if you reference the entity in another entity, it maintains its own case sensitivity setting.

Most entities in the standard grammars do not have case sensitivity set explicitly, giving you the flexibility to use case sensitivity as required in your grammars.

NOTE: If you design an entity for case insensitive matching, it is important that entries in the entity have a consistent case style to ensure that all matches are extracted correctly. You should use all lower case, all upper case, or all initial capitals, but not a mixture.

Named Entity Recognition uses an optimization technique for case insensitive matching that might not extract every possible match if you do not define the entity consistently.

## Case Normalization

Case sensitive matching generally has better performance than case insensitive matching. When you require case insensitive matching, you can use case normalization to give the same performance as case-sensitive matching.

When you want to use case normalization:

- Do not set case sensitivity explicitly in grammars and entities.

- Set the `MatchCase` configuration parameter to `True`.

- Create all entries in your entities in either all lower case, or all upper case.

- Set `CaseNormalization` to:

  - `LOWER` if all your entities are lower case.
  - `UPPER` if all your entities are upper case.

Named Entity Recognition normalizes the input data accordingly before the (case sensitive) matching. This process means that both your input and grammars are all in the same case, so the matching is effectively case insensitive, with the performance benefits of case sensitive matching.

For more information about these configuration parameters, see CaseNormalization and MatchCase.

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Version 25.3 | Last updated July 2025

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Product: Knowledge Discovery Named Entity Recognition 25.3

Topic Title: Case Sensitive Matches