dtSearch Text Retrieval Engine Programmer's Reference
dtsFileSpec Structure

Used to define a set of files to search or index

File: dtsearch.h

struct dtsFileSpec { const char * includeFilters; const char * excludeFilters; char dir[FileNameLen]; char dirListName[FileNameLen]; char fileListName[FileNameLen]; const char * dirList; };

fileListName provides a way to simply pass a list of files to search or index. 

Alternatively, the calling program can ask dtSearch to list the files in one directory (the dir member) or in a list of directories (the dirListName member), using the supplied include and exclude filters. 

To specify a directory and all subdirectories, add a <+> symbol at the end, like this: C:DOCS<+>