Editing Consistency model (section)

==== RCsc and RCpc ====

There are two types of release consistency, release consistency with sequential consistency (RCsc) and  release consistency with processor consistency (RCpc). The latter type denotes which type of consistency is applied to those operations nominated below as special.

There are special (cf. ordinary) memory operations, themselves consisting of two classes of operations: ''sync'' or ''nsync'' operations. The latter are operations not used for synchronisation; the former are, and consist of ''acquire'' and ''release'' operations. An acquire is effectively a read memory operation used to obtain access to a certain set of shared locations. Release, on the other hand, is a write operation that is performed for granting permission to access the shared locations.

For sequential consistency (RCsc), the constraints are:
* acquire → all,
* all → release,
* special → special.

For processor consistency (RCpc) the write to read program order is relaxed, having constraints:
* acquire → all,
* all → release,
* special → special (except when special write is followed by special read).

Note: the above notation A → B, implies that if the operation A precedes B in the program order, then program order is enforced.