Directory pattern (transformation scope)
Directory pattern field is used to specify a directory to which LinkFreeze transformation settings will be applied. This is used to limit processing of LinkFreeze and to protect other areas fo your site from possible conflicts with transformation scheme. When you specify a directory, only links on pages withing this directory will be modified, and also only requests to this directory will be transcoded back to the dynamic form.
To apply transformation for entire site leave '/' in this field. To apply transformtation to some directory use /directory/subdirectory syntax.
We say directory to simplify things, but actually it is a URI pattern. You may specify here not only exact directory names, but also parts of file names. You may use ? and * wildcard characters here. Even more you can use a @regex syntax to specify a regular expression for more flexible matching. Here is a few examples of a regular expression patterns for Directory field:
@[^?]+\.asp - this will match every .asp file on the site.
@/(?!images|css|script).* - this one will match all site content except /images, /css and /script folders.
You can read more about regular expression syntax in ISAPI_Rewrite product documentation.