Mask and Rev-Mask (Reverse-Mask) are aytm Logic commands that reduce the number of options presented in a question based on previously selected answer options.

Most commonly used following Checkbox or Multichoice Progressive Matrix question types, where both the original and follow-up questions have identical answer lists. Answer 1 in the referenced question should align to option 1 in the masked question, answer 2 to option 2, and so on. If the number of options differs between the two questions, the extra options are ignored by the masking rules.

The follow-up (masked or rev-masked) question can be another question type — such as a radio button, reorder/ranking, or other subquestions within a matrix.

Mask Logic

Use Mask to show only the answer options that were selected by the respondent in a previous question. This logic must be placed in the follow-up question.

Syntax: [mask by...]
Example: [mask by Q3]

Rev-Mask Logic

Use Reverse-Mask to show only the answer options that were not selected by a respondent in a previous question. This logic must be placed in the follow-up question.

Syntax: [rev-mask by...]
Example: [rev-mask by Q3]

Using Except

If there's an option you want to always show in the follow-up question regardless of whether it was selected in the original question — for example, "None of the above" or "Other" — use except in your logic string.

This logic must be placed in the follow-up question. The reference following except must refer to the question the logic is placed in, not the referenced question.

Examples:
[mask by Q3 except Q4A15]
[rev-mask by Q3 except Q4A15]

⚠️ Note: In the examples above, using Q3A15 as the except reference would not work — the except reference must point to the question containing the logic (Q4), not the source question (Q3).