Info: (as) If

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as: If

 
 7.44 '.if ABSOLUTE EXPRESSION'
 ==============================
 
 '.if' marks the beginning of a section of code which is only considered
 part of the source program being assembled if the argument (which must
 be an ABSOLUTE EXPRESSION) is non-zero.  The end of the conditional
 section of code must be marked by '.endif' ('.endif' Endif.);
 optionally, you may include code for the alternative condition, flagged
 by '.else' ('.else' Else.).  If you have several conditions to
 check, '.elseif' may be used to avoid nesting blocks if/else within each
 subsequent '.else' block.
 
    The following variants of '.if' are also supported:
 '.ifdef SYMBOL'
      Assembles the following section of code if the specified SYMBOL has
      been defined.  Note a symbol which has been referenced but not yet
      defined is considered to be undefined.
 
 '.ifb TEXT'
      Assembles the following section of code if the operand is blank
      (empty).
 
 '.ifc STRING1,STRING2'
      Assembles the following section of code if the two strings are the
      same.  The strings may be optionally quoted with single quotes.  If
      they are not quoted, the first string stops at the first comma, and
      the second string stops at the end of the line.  Strings which
      contain whitespace should be quoted.  The string comparison is case
      sensitive.
 
 '.ifeq ABSOLUTE EXPRESSION'
      Assembles the following section of code if the argument is zero.
 
 '.ifeqs STRING1,STRING2'
      Another form of '.ifc'.  The strings must be quoted using double
      quotes.
 
 '.ifge ABSOLUTE EXPRESSION'
      Assembles the following section of code if the argument is greater
      than or equal to zero.
 
 '.ifgt ABSOLUTE EXPRESSION'
      Assembles the following section of code if the argument is greater
      than zero.
 
 '.ifle ABSOLUTE EXPRESSION'
      Assembles the following section of code if the argument is less
      than or equal to zero.
 
 '.iflt ABSOLUTE EXPRESSION'
      Assembles the following section of code if the argument is less
      than zero.
 
 '.ifnb TEXT'
      Like '.ifb', but the sense of the test is reversed: this assembles
      the following section of code if the operand is non-blank
      (non-empty).
 
 '.ifnc STRING1,STRING2.'
      Like '.ifc', but the sense of the test is reversed: this assembles
      the following section of code if the two strings are not the same.
 
 '.ifndef SYMBOL'
 '.ifnotdef SYMBOL'
      Assembles the following section of code if the specified SYMBOL has
      not been defined.  Both spelling variants are equivalent.  Note a
      symbol which has been referenced but not yet defined is considered
      to be undefined.
 
 '.ifne ABSOLUTE EXPRESSION'
      Assembles the following section of code if the argument is not
      equal to zero (in other words, this is equivalent to '.if').
 
 '.ifnes STRING1,STRING2'
      Like '.ifeqs', but the sense of the test is reversed: this
      assembles the following section of code if the two strings are not
      the same.