MACRO-64 source statements can have a maximum of four fields, as
    follows:

    o  Label field-Symbolically defines a location in a program.

    o  Operator field-Specifies the action to be performed by the
       statement; this can be an instruction, an assembler directive,
       or a macro call.

    o  Operand field-Contains the instruction operands or the
       assembler directive arguments or the macro arguments.

    o  Comment field-Contains a comment that explains the meaning of
       the statement; this does not affect program execution.

    You can separate statement fields by either a space or a tab
    stop, but Digital recommends that you format statements with the
    Tab key to ensure consistency and clarity.

    Table 1 Using Tab Stops in Statement Fields

              Column
              in
              Which
              Field
    Field     Begins   Tab Stops to Reach Column

    Label     1        0
    Operator  9        1
    Operand   17       2
    Comment   41       5

    The following example shows a typical source statement:

    EXP:    .BLKL   50           ; Table stores expected values
    Rules for Coding Source Statements
    The following rules apply for coding source statements:

    o  You can continue a single statement on several lines by
       using a hyphen (-)  as the last nonblank character before
       the comment field, or at the end of line (when there is no
       comment).

    o  In most cases, you can continue a statement at any point. If a
       symbol name is continued and the first character on the second
       line is a tab or a blank, the symbol name is terminated at
       that character.

    o  Blank lines are legal, but they have no significance in the
       source program except that they terminate a continued line.

    The following sections describe each of the statement fields in
    detail.