$$$Temporary file created by the Definitions Editor or SORT.
AFDThis is the File Definition created by SUBFILE, which                           extracts a new file from an existing data file.
BFDThe Backup File Definition produced by EDITFD.  Normally,                       you don't need an entry for this, because it is created on                      the same disk where the FD file resides. UTILITY will ask                       however.     
BMDThe Backup Menu Definition created by EDITMD.  Normally,                        you need not have an entry for this, because it is created                      on the same disk where the MD file resides.
BRDBackup Report Definition, produced by EDITRD.
BSDBackup Screen Definition, produced by EDITSD.
CMDA batch command file.  This extension is interchangeable                        with SUB.
CTLControl definition, created by DEFSORT
DATA data file. This is the default extension for all data                         files.  You can specify your own extension for printing                         or sorting, but not for the UPDATE process, unless ALONE                        invocations
DDDThis controls the date format collected by DATE and print-                      ed on reports. 'S' is standard MMDDYY.                                          'I' is international DDMMYY, and 'Y' is YYMMDD.
E  The compiled EFM program, executable by DO
EFMAn EFM source code file.
FD The File Definition.
IDXAn Index.  Contains the data file name, FD name, and all                        of the CTL definition.  Can refer to any kind of file. See                      LOCATE.IDX for example.
IIIIf you put a space in for the drive name, UPDATE will                           sort the index after it is created.  This is necessary                          only if key fields contain mixed upper and lower case.
LLLDummy extension to control page length, as used by all                          printing programs except REPORT.
MD A Menu Definition
MNTDummy extension used to reduce operator intervention. If                        you specify a space as the drive name, you won't be asked                       for anything by SORT, REPORT, or APPLY1.
NEWTemporary file created during the UPDATE process.
NNNIf you put in a space for the drive name, SORT will always                      overwrite its input file, eliminating the need to rename                        a .SRT file whenever you sort something.
OLDTemporary file created during the UPDATE process.
RD Report Definition (referred to as the REPORT file by                            the menus)
REJRejected transaction file, created by APPLY1.  Can be                           processed by TRANSACT.
SD Screen Definition
SELSelection Definition
SFLA subfile created by SUBFILE, which extracts data from                          an existing data file into a new data file.
SRTOutput from SORT.  Index files and transaction files                            (.TRX and .REJ) are automatically over-written by SORT.                         If you use the NNN dummy extension, you can make all files                      over-written.
SSSEnter a space for the drive name, and PRINT will not                            put a blank line after each record.  Use any other charac-                      ter, and it will.
SUBA batch command file.  This extension is interchangeable                        with CMD.
SYSOne of the system files.  If a .SYS file is used as a .SYS                      file, (normal usage), the LOCATE entry is ignored.  But if                      you use it as a data file (as with the LOCATE maintenance)                      enter a drive
TRXTransaction file.
WWWDummy extension to control page width, as used by all of                        the printing programs except REPORT.
XXXUse a space for the drive name, and UPDATE will refrain                         from printing transactions. Use any other character and                         transactions will be printed after they are sorted.