# InvalidRegexBeforeMatch

A regular expression that cannot form part of the valid match for a pre-filter.

When Eduction runs a pre-filter task, it finds a potential match and creates a match window by selecting characters before and after the potential match (you configure the size of the match window by using WindowCharsAfterMatch and WindowCharsBeforeMatch). You can use `InvalidRegexBeforeMatch` to specify a pattern that definitely cannot form part of a valid match. When Eduction finds something that matches this non-valid pattern in the match window before the potential match, it truncates the match window to exclude the non-valid pattern and any text before it.

For example, if you know that your pattern can only include space characters, letters, and numbers, you can use the following setting to truncate the match window if Eduction finds anything else:

`InvalidRegexBeforeMatch=[^ \p{L}\p{N}]`

Type: | String
Default: |
Required: | No
Configuration Section: | MyPreFilterTask
Example: | `InvalidRegexBeforeMatch=[^ \p{L}\p{N}]`
See Also: | Regex ResourceFile WindowCharsAfterMatch WindowCharsBeforeMatch

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