% @(#)do.mlq	17.1.1.1 (ESO-IPG) 01/25/02 17:43:23
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SECTION./
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DO							21-JAN-1993  KB
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DO loopvar = start end [step]
	define a DO loop (as in FORTRAN)
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Purpose:  
          Define a DO loop (as in FORTRAN).
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Syntax: 
          DO loopvar = start end [step]
\ys\pa
          loopvar = name of integer keyword serving as loop variable
\ap\pa
          start = starting integer value of loop, either integer constant or
             name of integer keyword
\ap\pa
          end = end integer value of loop, either integer constant or
             name of integer keyword
\ap\pa
          step = optional integer stepsize, either integer constant or
             name of integer keyword; defaulted to 1
\ap\no
Note:   
          The DO block must be closed with an ENDDO command; please, note
          that contrary to FORTRAN the ENDDO must(!) be written as one word,
          i.e.  END DO  results in an error ...
\\
          Nested loops are supported up to 8 levels deep.
\\
          A DO loop is executed at least once, i.e. the test for loop
          termination is done in the end of the DO block.
\\
          A stepsize = 0 is legal and leads to an infinite loop unless the 
          start value is already larger than the end value.
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Examples:
\ex
{\tt
          DEFINE/LOCAL LL/I/1/1 0\\
          DO LL = 12 22 2\\
             WRITE/KEY INPUTI/I/{LL}/1 {LL}\\
          ENDDO
}
            This would fill keyword INPUTI(12,14,...,22) with the values
            12,14,...,22.
\xe\ex
{\tt
          DEFINE/LOCAL LL/I/1/1 0\\
          OUTPUTI(4) = 10\\
          DO LL = 22 OUTPUTI(4) -2\\
             WRITE/OUT {LL}\\
          ENDDO
}
            This would display the numbers 22, 20, ..., 12, 10.
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