Re: st: Need help with working with multiple files

[Nick Cox <njcoxstata@gmail.com>]

If you refer to a macro that doesn't exist Stata doesn't regard that
as an error: it just substitutes nothing, or equivalently ignores the
reference.

Nested macro references don't affect this principle and indeed must be
consistent with it. So if  local macro x does not exist as a string to
be used neither do any of

`x'
``x''
```x''''

and so forth. You could say that they define empty strings if you
like, but the effect is the same: a non-existent string and an empty
string look identical.