Mask and Rev-Mask (short for Reverse-mask) are aytm Logic commands that allow users to reduce the number of options presented in a question based on previously-selected answer options.
Most commonly, these commands are used following Checkbox or Multiple choices Progressive Matrix question types, where both the original question and the follow up question have identical answer/option lists. In other words, answer 1 in the referenced question should align to option 1 in the masked question, answer 2 in the referenced question should align to option 2 in the masked question, and so on. If there are more options in the referenced question than in the masked question or vice versa, those additional options are ignored by the masking rules.
However, the follow-up (masked or rev-masked) question may be another type of question, such as a radio button, reorder/ranking, other sub-questions within a matrix question, etc.
Use Mask logic to show only 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...]
Use Reverse-Mask logic to show only 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]
When there is an option that you would like to include in the follow-up question, regardless of its selection or inclusion in the original question (for example, a "none of the above" or "other" option), you can show that by using Except in your logic string.
This logic must be placed in the follow-up question, and note that the reference following the Except command must contain the reference to the question the logic is placed in (i.e. in the below example, the reference Q3A15 would NOT work).
Example: [mask by Q3 except q4a15] or [rev-mask by Q3 except Q4A15]