@node Whatis, While, Viewpoint, Commands

@iftex
@syntax Whatis.
@end iftex
@example
Syntax: Whatis ( expr )
@end example
@pindex Whatis
@findex classifying strings

WHATIS(something) has a value depending on what something is:
@example
a number:       0
not a number:           set 01 bit    (bit 0)
  a macro:              set 02 bit    (bit 1)
  a variable:           set 04 bit    (bit 2)
  a vector:             set 010 bit   (bit 3)
     a float vector:    set 040 bit   (bit 5)
     a string vector:   set 0100 bit  (bit 6)
  a keyword:            set 020 bit   (bit 4)
@end example
@noindent
So if ``aa'' is the name of a string vector, WHATIS(aa) has the octal
value 0111, or 73, 
whereas WHATIS(HELP) has the value 021, or 17, and WHATIS(1) is 0.
There is a macro in @file{utils} called @code{is_set} that tests if WHATIS
sets a particular bit, for example
@example
	if(is_set(kkk,3)) @{ echo kkk is a vector @}
@end example
@noindent
tests if bit 3 (vector) is set for ``kkk'' and prints its findings;
it's easier to say
@example
	if(is_vector(kkk)) @{ echo kkk is a vector @}
@end example
which does the test for you.