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 One of the many pseudo-macros that must be immediately followed by a <tab-id>,
this conditonal pseudo obeys the following 2 chars (which must always be there)
in the macro if the cursor is before (and not at) the character numbered by the
tab <tabid>. Type 'H CP' for more details on cursor position. Type 'H AS' for
the list of tab id's.
 Example:-
 If tab # 1 is 7 (as at start-up) and you have defined macro ^A as follows:
 N A ^NB1^N^B^NU
 I.E. goto macro ^B if ^NB1 is true otherwisw exit, then if the cursor is at
character 6 or earlier ^N^B will be invoked otherwise it won't. At position 7,
both ^NB and its opposite ^NP are false, which can be used to test for
equality.
 Note
 Attempting to test against a tab which has never been set is illegal, and
rings the bell, also quitting the macro.
