Hi pl,

This is from the documentation:

For all entity types, every record has an id field that uniquely identifies that record. The value for the id field is created automatically upon insert, and it cannot change over the lifetime of that record, even if the record is deleted and then undeleted. Each id value is guaranteed to be globally unique. The id of a record is the best way to uniquely identify that record.

In API versions prior to 2.0, the id of a record is always a 15 character case-sensitive ID and should not be compared in a case-insensitive manner.

In API versions 2.0 and higher, the API can return either a case-sensitive or a case-insensitive id field value. The case-insensitive ID is identical to the 15 character case-sensitive ID with three extra characters appended to indicate the case of each of the original 15 characters. When inserting or updating records, the API accepts either the 15 character case-sensitive ID or the 18 character case-insensitive ID. When querying or searching records using the API, you must specify a value of �1� for the �useCaseSafeIDs� parameter to indicate that you want the API to return case-insensitive IDs. If you do not specify the �useCaseSafeIDs� parameter, you automatically receive case-sensitive IDs.

The ID of a record also indicates what type of entity it is. This is useful for the search response that returns a list of record IDs but does not include the entity type for each record (see The search Response for more information). Every record ID begins with a three character code that identifies the entity type. The three character codes are: