Robots.txt Allow sub folder but not the parent

Question

Can anybody please explain the correct robots.txt command for the following scenario.

I would like to allow access to:

/directory/subdirec

Answer 1

Be aware that there is no real official standard and that any web crawler may happily ignore your robots.txt

According to a Google groups post, the following works at least with GoogleBot;

User-agent: Googlebot 
Disallow: /directory/ 
Allow: /directory/subdirectory/