Hash

A Runtime Resource ID, or simply RuntimeID, or often just a "hash", is a unique identifier for a specific game resource. It is used to reference resources across the game's files.

RuntimeIDs (or hashes) are 16 characters long, and always begin with 00. The rest of the hash is hexadecimal (numbers 0-9 plus letters A-F) and is calculated using mathematical formulas from the original path of the game file (if you're interested, it's a truncated MD5 hash).

For example, the resource [assembly:/templates/gameplay/ai2/actors.template?/npcactor.entitytemplate].pc_entitytype represents an NPC, and is incorporated into level files to add NPCs to them. The hash for this resource is 00DDCC74AD917CAA; all references to this resource in the game use that hash, and it uniquely represents the resource.

We know the original paths for most resources in the game. Some of these were included in the game itself, some have been guessed based on their contents (and then checked against the hash, since the hash is derived from the path). We don't know all the original paths though; that's why you'll see some resources only shown as a hash or a hint (some short descriptive text).