# How does the Raw Text Filter option work in file sources in Astera?
The Raw Text Filter option is available in the [*Fixed Length* *File Source*](/astera-data-stack-v10/dataflows/sources/fixed-length-file-source.md) and [*Delimited File* *Source*](/astera-data-stack-v10/dataflows/sources/delimited-file-source.md) properties.
*Raw text filter* is used to filter out the incoming records which you do not want to process in your Dataflow. This option is also useful in processing files that contain multiple record types. It also provides the flexibility to source selected data by applying filters at the point of extraction, without modifying the original source data in any way. You can choose from the following three options to filter data:
*No filter. Process all records:* This is the default option, and it processes all the records from the source without filtering them out.
*Process if begins with:* This option filters out records that start with a certain letter, digit, character, word, numeric value, or phrase.
*Process if matches the regular expression:* This option is useful if you want to use a regular expression to extract matching records.
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