Publisher Item Identifier
A Publisher Item Identifier (PII) is a standard identifier number system which identifies a published document. It was created in 1996, agreed and developed by the American Chemical Society, the American Institute of Physics, the American Physical Society, Elsevier Science, and the IEEE. Although, PII has currently been included in Digital Object Identifier (DOI)® system (as a syntaxe in the DOI suffix) for Crossref publishers using De facto identifier method, but many of publishers like AMS, still rely on original, facil and free of charge method of creating the Article Unique Identifiers like PII.
Digital Object Identifier (DOI): A name (not a location) for an entity on digital networks. DOI names are used to provide current information, including where they (or information about them) can be found on the Internet.
Publisher Item Identifier (PII): Alphanumeric string of characters that uniquely identifies the article and can be used for future cataloging, searching, and electronic retrieval (Free of Charge). An article explaining the PII numbering system can be found on: http://en.wikipedia.org/wiki/Publisher_Item_Identifier
The highlighted items are those published
Article 01: S2322455X2000001-10