5.13.6 Implementation-Specific Information This section describes some implementations of stream I/O in REXX. Unfortunately, this has become a very large section, reflecting the fact that stream I/O is an area of many system-specific solutions. In addition, the variations within this topic are rather large. Regina implements a set of functions that are very close to that of TRL2. The other extreme are ARexx and BRexx, which contain a set of functions which is very close to the standard I/O library of the C programming language.