Apparently related to the Password Hashing Competition that selected Argon2 as the winner in 2015, PHC string format can be considered a subset or profile of MCF. It is more thoroughly specified than MCF. It has nice properties that enable the creation of a BMCF definition that could be reused for all PCH string format–compatible schemes:
it defines a concrete format with four fields: $<id>[$<param>=<value>(,<param>=<value>)*][$<salt>[$<hash>]]
it defines the legal characters for id, param, and value
it specifies a max length for id and param
it designates RFC 4648 Base64 (without = padding) as the encoding to use for the hash digest
although it does not require the same encoding for the salt, it does define the legal characters for the salt
Apparently related to the Password Hashing Competition that selected Argon2 as the winner in 2015, PHC string format can be considered a subset or profile of MCF. It is more thoroughly specified than MCF. It has nice properties that enable the creation of a BMCF definition that could be reused for all PCH string format–compatible schemes:
$<id>[$<param>=<value>(,<param>=<value>)*][$<salt>[$<hash>]]id,param, andvalueidandparam=padding) as the encoding to use for the hash digest