URN
Uniform Resource Identifier (URI) that uses the urn scheme
International Standard Book Number
unique numeric book identifier
International Standard Serial Number
unique eight-digit number used to identify a print or electronic periodical publication
Lex
URN namespace, a type of Uniform Resource Name, that allows accurate identification of laws and other legal norms
International Standard Audiovisual Number
unique identifier for audiovisual works and related versions, similar to ISBN for books
National Bibliography Number
publication identifier systems used by national libraries
Entertainment Identifier Registry
global unique identifier system for audio visual objects
Life Science Identifier
specification