[O] limitation for macro expansion

[Yasushi SHOJI]

Hi,

I'm can't expand macro with prefix.  Is there any limitation for macro
expansion listed in the doc?

* test
- It works with chars around like this: Aa{{{author}}}bB.
- It works with numbers around like this: 12{{{author}}}34.
- It works with _ around like this: _{{{author}}}_.
- It works with =__= around like this: __{{{author}}}__.
- But it doesn't work with 'a_' prefixed like this: a_{{{author}}}.
- But it doesn't work with '1_' prefixed like this: 1_{{{author}}}.
- Link doesn't work like this: [[file:{{{input-file}}}][Bad link]]

Thanks,
--
          yashi