RPX abbreviation expansion?

Does anyone know if RPX is an abbreviation开发者_C百科 for something or just a name?

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This FAQ says:

What does RPX stand for?

Relying Party Accelerator. From the OpenID 2.0 specification, a Relying Party is ...

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According to this site (no idea how credible) it is "Relying Party X".

Context - "...RPX takes advantage of this and provides a middleman for the user depending on which service they selected they would like to use to login. The name means Relying Party X"