Mask

1) Data entry

A pattern that defines the characters that can legally be used in a data entry field. Often this is defined in a regular expression (regex).

2) Graphics

An outline that defines an area of a graphic that can either accept or reject pixels. Often a mask is applied to an existing picture to overlay an element (e.g., a frame mask with a transparent center can be overlaid on a bitmap to mask out the edges and replace them with the frame image, leaving the center of the original image intact.

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