syntax command, details (2)

+--------------------------------------------------------+
|          `0'           | `1'  |  `2'   | `3' |  `4'    |
|------------------------+------+--------+-----+---------|
| mpg wei if foreign     | mpg  |  wei   | if  | foreign |
+--------------------------------------------------------+
           |          (macros `0', `1', ... remain unchanged)
           |
  syntax [varlist] [if]
   reads `0' and fills      <-- syntax just knows to read `0'
   in `varlist' and `if'
           |
           |            +--------------------------------+
           |            |   `varlist'       |   `if'     |
           |            |-------------------+------------|
           |            | mpg weight        | if foreign |
           |            +--------------------------------+
           |              ^^^^^^^^^^          ^^^^^^^^^^
           |                   |                   |
           +----->---->--------+--------->---------+
                      (syntax fills in `varlist' and `if' because
                        the command was syntax [varlist] [if])
                                                ^^^^^^^   ^^