names beginning with IFC and IM*, but IBM changed the naming convention to HM* for OS/VS1 and to AM* for OS/VS2. IBM did not change the IFC convention. IFCDIP00 Initializes the SYS1.LOGREC data set. IFCEREP0 Summarizes and prints records from the SYS1.LOGREC error recording data set. GTF (Generalized Trace Facility) Traces selected system events such as SVC and I/O interruptions. IMAPTFLE Generates JCL needed to apply to a PTF and/or applies the PTF. The functions of this program have been subsumed by SMP. IMASPZAP Verifies and/or replaces instructions and/or data in a load module, program object, or disk file. IMBLIST Formats and prints object modules, load modules, program objects and CSECT identification records. IMBMDMAP Maps load modules. The functions of this program have been subsumed by IMBLIST. IMCJQDMP Stand-alone program to format and print the system job queue. Not applicable to MVS. IMCOSJQD Format and print the system job queue. Not applicable to MVS. IMDPRDMP Formats and prints core dumps, TSO swap data set, and GTF trace data. IMDSADMP Stand-alone program to produce a high-speed or low-speed dump of main storage. Miscellaneous supporting programs SORT The Sort/Merge utility is a program which sorts records in a file into a specified order, or merge pre-sorted files. It is very frequently used; often the most commonly used application program in a mainframe shop. Modern sort/merge programs also can select or omit certain records, summarize records, remove duplicates, reformat records, and produce simple reports. Sort/merge is important enough that there are multiple companies each selling their own sort/merge package for IBM mainframes. IBM's original OS/360 sort/merge program, 360S-SM-023, program name IERRCO00 (alias SORT), supported only IBM's first-generation direct-access storage devices (DASD) and tapes (2400). Support for second-generation disk drives was provided by IBM program products such as 5734-SM1 and the later 5740-SM1 (DFSORT, alias ICEMAN, also SORT). SORT is frequently executed as a stand-alone program, where it normally reads input from a file identified by DD SORTIN and writes sorted output to a file identified by DD SORTOUT. It is also often called from another application, via the COBOL SORT verb or calls to PL/I PLISRTx routines, where it may use either SORTIN or SORTOUT files or be passed records to be sorted by the caller and/or pass sorted records back to the caller one at a time. The operation of SORT is directed by control statements, which are largely compatible among various