Whenever any Subfile is opened by an application program , TPFDF retrieves the file information of the file from the central database definition table and copies information into an internal workarea called as the Database Interface Block (DBIFB)
The DBIFB has several slots in it , One for each opened Subfile , The SWOOSR Slot hence functions as the working copy of the DBDEF table and maintains information relevant to the current status of operations on the Subfile
The Base of the SWOOSR Slot is always Register R3 , Hence all programs using TPFDF need to code SW00SR REG=R3 , at the beginning of the program , Also "Do Remember that TPFDF hence Reserves register R3 For its use "
Important SW00SR DSECT Fields
SW00SR FIELD DISPLACEMENT DESCRIPTION
SW00WID 010 2 Byte Record ID of required File
SW00FAD 044 4 Byte File address of Prime Record
SW00RTN 081 1 Byte TPFDF Command Return Indicator
SW00REC 084 4 Byte Address of Located Record
SW00RT2 0DB 1 Byte 2nd Return Indicator
SW00WKA 260 4 Byte Address of Workarea
Also Available are 2 user fields , SW00USI a 1-Byte user Indicator Field and SW00USA a 4-Byte user address field
