Vertical bar and comma in hash function input I came across to a definition of a term PMKID while studying 4-way handshake in IEEE 802.11i. It is defined as:

PMKID = H(PMK,"PMK name"||AA||SPA)

I know the vertical bar || in the input of the hash function means concatenation, i.e. joining them end-to-end. How about the comma? Any difference?

And also, does "PMK name" means that the string is converted into binary form and serve as part of the input or is it there for demonstration purpose only?
I don't know anything about IEEE 802.11i, so I can't be sure about my answer, but hopefully this provides some insight.

From the way in which the formula is written, $H$ is probably some sort of keyed hash algorithm—probably HMAC.  HMAC takes two parameters: the secret key to the MAC and the data to hash.  The first parameter is probably the secret key to HMAC, with the concatenated data being the data to hash with HMAC.