Limitiations of CF90 version 3.1 Co-Array Fortran

1. Co-arrays must have elements that are 64-bits and aligned on 64-bit memory boundaries. In particular, REAL*4 or REAL(KIND=4) and all COMPLEX types are not allowed.
2. A STOP on one image does not cause all images to cease execution.
3. A dummy co-array argument cannot have assumed size local dimensions.
4. A dummy co-array argument cannot have assumed shape local dimensions.
5. Subscript triplet and vector subscript notation is not allowed in square brackets.
6. Square brackets may be used in references to components of derived type co-arrays, but square brackets are not allowed when referencing the entire derived type.
7. Co-Array Fortran I/O extensions to Fortran 95 are not supported. Instead, each image has its own independent I/O units.
8. The CF90 3.1 manual makes no mention of SYNC_MEMORY() or caf-procedures. It is not clear if the compiler follows the language standard's rules for co-array synchronization.
9. The intrinsics END_CRITICAL, START_CRITICAL, SYNC_ALL, SYNC_FILE, SYNC_TEAM, and SYNC_MEMORY are not supported. Note: A user-level implementation of the missing intrinsics is available and should be used for portability.
10. The intrinsic SYNC_IMAGES is provided as an extension to the standard language.
    • SYNC_IMAGES() is equivalent to SYNC_ALL().
    • The general case, SYNC_IMAGES(IMAGE), is an alternative synchronization primitive to SYNC_TEAM. It is more general in some ways, but harder to use and less efficient (because it does not support WAIT).