help wfmissing: Suggested uses for extended missing values

Suggested meanings for extended missing values

. Sysmiss; unspecified reason for missing data.

.d Don't know.

.l Do not use since easy to confuse with 1 (one).

.n Not applicable, such as only adults were asked question.

.p Preliminary (i.e., lead in) question refused.

.r Refused to answer.

.s Skipped due to skip pattern.

.t Technical problem such as read error on mark sense form.

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