For what it's worth, I was surprised to discover that
 lookfor myvar, fullnames
produces the same result as
 lookfor myvar fullnames
That is, if you add any options to -lookfor-, it ignores the
comma and treats the options as search strings.
On the one hand, the documentation clearly indicates there
are no options. On the other, it often happens that I try
options that I think might work and expect Stata complain
if they are invalid.
In this case, I abbreviated -fullnames- to -fu-, and was finding 
variables that in no way matched -myvar-. Took me a while to
puzzle out.
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