AIPS HELP file for TXINC in 31DEC09
TXINC
Type: Adverb (Real)
Use: The increment associated with an array of numbers. When
used with TYINC, TXINC generally refers to the first
coordinate (columns) of an image. TXINC is used with TV
verbs, but is otherwise the same as XINC.
Null value: 0
Null value assignment generally means 1.