3. Invalid SVC 203 code. If an invalid code follows SVC 203 inline, then an
error message is displayed, and the abend routine is called to terminate exe­
cution. Search Hierarchy for SVC 202 When a issues SVC 202, passing a routine or command name in the
parameter list, then DMSITS searches for the specified routine or command. (In
the case of SVC 203 with a zero in the table entry for the specified index, the same
logic must be applied.)
Figure 38 , Part 2, shows the search logic following and SVC 202 call.
The search algorithm is as follows:
1. A check is made to determine if the specified name is known dynamically to CMS through the SUBCOM function.
2. A check is made to see if the specified name is a nucleus extension routine. If
this is the case, the control goes to the specified nucleus extension routine.
Note: This step is skipped if the high-order byte of register 1 contains X'03.' or
X'04'. X'03' indicates that an extended plist is provided. X'04' indicates that
a tokenized plist is provided. For both X'03' and X'04', values are translated
to X'01' and X'OO', respectively, by the SVC interrupt handler before the
called program is entered.
3. A check is made to see if there is a routine with the specified name currently
occupying the system transient area. If this is the case, then control is trans­
ferred there.
4. The system function name table is searched, to see if a command by this name
is a nucleus-resident command. If the search is successful, control goes to the
specified nucleus routine.
5. A search is then made for a disk file with the specified name as the filename,
and MODULE as the filetype. The search is made in the standard disk search
order. If this search is successful, then the specified module is loaded (via the
LOADMOD command), and control passes to the storage location now occu­
pied by the command.
6. If all searches so far have failed, then DMSINA (ABBREV) is called, to see if
the specified routine name is a valid system abbreviation for a system com­
mand or function. User-defined abbreviations and synonyms are also checked.
If this search is successful, then steps 2 through 5 are repeated with the full
function name.
7. If all searches fail, then an error code of -3 is issued.
Commands Entered from the Terminal
When a command is entered from the terminal, DMSINT processes the command
line, and calls the scan routine to convert it into a parameter list consisting of
eight-byte entries.
Functional Information 339

See Figure 38 for a description of this search for a command name. The following
search is performed:
1. DMSINT searches for a disk file whose filename is the command name, and
whose filetype is EXEC. If this search is successful, EXEC is invoked to proc­
ess the EXEC file.
If not found, the command name is considered to be an abbreviation and the
appropriate tables are examined. If found, the abbreviation is replaced by its
full equivalent and the search for an EXEC file is repeated.
2. If there is no EXEC file, DMSINT executes SVC 202, passing the scanned
parameter list, with the command name in the first eight bytes. DMSITS per­
forms the search described for SVC 202 in an effort to execute the command.
3. If DMSITS returns to DMSINT with a return code of -3, indicating that the
search was unsuccessful, then DMSINT uses the CP DIAGNOSE facility to
attempt to execute the command as a CP command.
4. If all of these searches fail, then DMSINT displays the error message UNKNOWN CP/CMS COMMAND. 340 VM/SP System Programmer's Guide