A KUID is a unique identifier that is assigned to an asset when it is created. This feature was introduced with Trainz 1.3 as an easy way of cataloging assets. There are two versions: KUID and KUID2. Pre-TRS2006 versions of Trainz require assets to be created manually and therefore KUIDs must be assigned manually. In TRS2006 and later CMP automatically assigns a KUID when you click 'new asset' or 'clone asset'.
A KUID in the original format is as follows:
<KUID:123456:123456>. The first set of numbers is the User ID of the author. A user's User ID can be accessed through their Planet Auran profile. A user is assigned a User ID when he or she registers with Planet Auran, and the User IDs are assigned in increasing numerical order. Most of them have either 5 or 6 digits, but some early ones can have 4 digits or less. The second set of numbers is a unique number set by the author and can be any number of digits. If creating or cloning an asset with CMP, CMP assigns numbers in the
1xxxxx range by default. For example, the first piece of content you create will be
<KUID:123456:100001> and so-on. With KUIDs, if an author had uploaded an asset to the DLS with
<KUID:123456:100001>, and they wished to update it, they would need to assign a new KUID to the updated asset i.e.
<KUID:123456:100002>. To replace asset number
100001 on the DLS, the obsolete asset's KUID must be recorded in the
obsolete-table section of the config file of the new asset. (discussed elsewhere). This can get confusing, and so a solution was devised in the form of KUID2.
a KUID2 is in a slightly different format as follows:
<KUID2:123456:123456:1>. As before, the first two numbers are the author's User ID and unique identifier. The third number is a version number. An asset can now be updated simply by adding to the version number, no other fiddling needed. The clever thing about KUID2s is that they can also apply to assets with KUIDs. For example if we take our asset
<KUID:123456:100001> and want to update it using a KUID2, it is simply a matter of altering the KUID of the updated asset to read
<KUID2:123456:100001:1> and the DLS will automatically flag the original asset as out of date and CMP will direct all downloaders of it to acquire the update.