as.info: Expressions

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Expressions

   An "expression" specifies an address or numeric value.  Whitespace
may precede and/or follow an expression.
   The result of an expression must be an absolute number, or else an
offset into a particular section.  If an expression is not absolute,
and there is not enough information when `as' sees the expression to
know its section, a second pass over the source program might be
necessary to interpret the expression--but the second pass is currently
not implemented.  `as' aborts with an error message in this situation.