Within the handle namespace, every identifier consists of two parts: its handle prefix, also known as a "naming authority", and a suffix or unique "local name" under the prefix. The prefix and suffix are separated by the ASCII character "/". An identifier may thus be defined as

<Handle> ::= <Handle Prefix> "/"<Handle Suffix>

For example, "10.1045/april2006-paskin" is an identifier (also known as a Digital Object Identifier (DOI), an implementation of the Handle System) for an article published in D-Lib Magazine. It is defined under the prefix (naming authority) "10.1045", and its suffix (local name) is "april2006-paskin".

Identifiers may consist of any printable characters from the Universal Character Set, two-octet form (UCS-2) of ISO/IEC 10646, which is the exact character set defined by Unicode v2.0. The UCS-2 character set encompasses most characters used in every major language written today. To allow compatibility with most of the existing systems and prevent ambiguity among different encoding, handle protocol mandates UTF-8 to be the only encoding used for handles. The UTF-8 encoding preserves any ASCII encoded names, which allows maximum compatibility to existing systems without causing naming conflict.

By default, handles are case sensitive. However, any handle service, including the global service, may define its namespace such that all ASCII characters within any handle are case insensitive.

The handle namespace can be considered as a superset of many local namespaces, with each local namespace having its own unique prefix. The prefix identifies the administrative unit of creation, although not necessarily continuing administration, of the associated handles. Each prefix is guaranteed to be globally unique within the Handle System. Any existing local namespace can join the global handle namespace by obtaining a unique prefix, with the resulting identifiers being a combination of prefix and local name as shown above.

Each prefix may have "sub" or derived prefixes. For example, once the prefix 12345 has been created, 12345.1 can be created. Derived prefix 12345.1 is therefore defined under prefix 12345. The syntax can be represented as "string.substring". In terms of Handle System technology, a derived prefix is a prefix in its own right and can be used any way that a primary prefix can be used, but typically it is used as one of a set of connected prefixes.

Derived prefixes are sometimes used by organizations that assign identifiers to different categories of content or objects that they wish to keep separate. They are also used for test purposes. There is no Registration Fee for derived prefixes; only an Annual Service Fee. Note that the use of derived prefixes is controlled by the Handle System Service Agreement.

The prefix and the suffix, or local name, are separated by the octet used for ASCII character "/" (0x2F). The collection of local names under a prefix is the local namespace for that prefix. Any local name must be unique under its local namespace. The uniqueness of a prefix and a local name under that prefix ensures that any identifier is globally unique within the context of the Handle System.

For more information on handle syntax, see the Handle System RFCs referenced in the Interface Specification.