StarTeam uses the MD5 hash of a file as the filename in its vault. (Pretty clever if ya ask me.)
The top level folders in the vault all have a two letter name. These names correspond with the first two letters of the MD5 hash. Each folder also has a one letter folder inside it for each letter and number. These correspond to the third letter of the hash. StarTeam uses this scheme to determine where to place the file.
So, for example, if you had a file whose MD5 hash was 0D0909082EF668C63FCD4437B9C787F7 then StarTeam would put it in its vault in the folder: /0D/0
Of course, you shouldn’t go messing around with the files in the vault. You should let StarTeam manage them.