API Reference > bentleyjs-core > Ids Ids Classes for working with unique identifiers. Classes Name Description TransientIdSequence Generates unique Id64String values in sequence, which are guaranteed not to conflict with Ids associated with persistent elements or models. Namespaces Name Description Guid The Guid namespace provides facilities for working with GUID strings using the "8-4-4-4-12" pattern. Id64 The Id64 namespace provides facilities for working with 64-bit identifiers. Type Aliases Name Description GuidString A string containing a well-formed string representation of a Guid. Id64Arg Used as an argument to a function that can accept one or more Id64Strings. Id64Array An array of Id64Strings. Id64Set A set of Id64Strings. Id64String A string containing a well-formed string representation of an Id64. Last Updated: 13 June, 2024