st: Unable to clear "invalid syntax r(197);" error in user-written .ado file

[Richard Herron <richard.c.herron@gmail.com>]

I wrote an .ado file to trim data in the left and right tails, but I
can't get past an "invalid syntax r(197)" error. My -syntax- line is
as follows.

* begin syntax line
    syntax varlist(numeric) [if] [in] ///
        [, Byvar(string fyear) Tail(real 0.5) Suffix(string tr)]
* end syntax line

I would like to use a -varlist- so that I can loop over the supplied
variables, but I can't clear the error using -varname- or by dropping
the -if- and -in- statements. I also tried making the options required
without defaults, but that didn't work either.

What is my misunderstanding of syntax? Thank you!

Below is the complete .ado file. I use Stata SE 11.2 (64 bit) on Windows 7.

* begin .ado file
*! 0.1 Richard Herron 10/3/2012
program atrim
    version 11.2
    syntax varlist(numeric) [if] [in] ///
        [, Byvar(string fyear) Tail(real 0.5) Suffix(string tr)]

    * rather than -bysort- twice below
    sort `byvar'

    * not necessary to tokenize; loop varlist
    foreach x of local varlist {

        * determine percentiles
        by `byvar': egen num = count(`x') if !missing(`x')
        by `byvar': egen ran = rank(`x') if !missing(`x')
        generate pct = 100 * (ran - 0.5) / num

        * replace tails with -sysmiss-
        generate test = if inrange(pct, `tail', `=100 - `tail'')
        generate `x'_`suffix' = cond(test, `x', .)

        * drop "temporary" variables
        drop num ran pct test

    }

    end
* end .ado file
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