A brief description of the CLI operation should illustrate this point.
When CLI receives a command line it parses the first entry on the
command line and then tries to open a queue using the parsed name.
If the open queue succeeds the command tail is written to the queue
and the CLI operation is finished.  If the open queue fails a file type
of PRL is entered for the parsed file name and a file open is
attempted.  If the file open succeeds then the header of the PRL
file is read to determine the memory requirements.
A relocatable memory request is made to obtain a memory segment in
which to load and run the program.  If this request is satisfied
the PRL file is read into the memory segment, relocated, and it is
executed, completing the CLI operation.
.PP
If the PRL file type open fails then the file type of COM is entered
for the parsed file name and a file open is attempted.  If the open
succeeds then a memory request is made for the absolute TPA, memory
segment based at 0000H.  If this request is satisfied the COM file is
read into the absolute TPA and it is executed, completing the CLI
operation.