MPI_REAL2 not always included in appropriate lists

[jeffhammond]

Problem

Chapter 19:

We assume that for each typeclass (integer, real, complex) and each word size n there is a unique machine representation. For every pair (typeclass, n) supported by a compiler, MPI must provide a named size-specific datatype. The name of this datatype is of the form MPI_ in C and Fortran where is one of REAL, INTEGER, or COMPLEX, and is the length in bytes of the machine representation. This datatype locally matches all variables of type (typeclass, n) in Fortran. The list of names for such types includes:
MPI_REAL4
MPI_REAL8
MPI_REAL16
MPI_COMPLEX8
MPI_COMPLEX16
MPI_COMPLEX32
MPI_INTEGER1
MPI_INTEGER2
MPI_INTEGER4
MPI_INTEGER8
MPI_INTEGER16

MPI_REAL2 and MPI_COMPLEX4 should be listed here, or we should remove the list altogether and just give an example, since a full list exists elsewhere.

Proposal

Add it to the list or remove the list.

Changes to the Text

Trivial

Impact on Implementations

None

Impact on Users

Clarity

References and Pull Requests

[wrwilliams]

+1 for remove list and add reference to the full list.

[jprotze]

Doesn't the includes: before the list already clarify that this is no complete list? I think, having 2 or three examples might be sufficient, or make the composition of the name more clear: MPI_XXXYYY, where XXX is in {INTEGER,REAL,COMPLEX} and YYY is the length in bytes without any 0 prefix.

[jeffhammond]

Sure, "includes" isn't technically wrong for listing 11 of 13 cases, but since it doesn't say "includes, for example", it is reasonable for a reader to conclude it is a complete list.

It is better to ambiguous, and that's what I'll accomplish in the change. Details TBD.