| Offsets | Name | Length | Format | Description | |
|---|---|---|---|---|---|
| 0 | 0 | SMF420MA | 76 | Structure | |
| 0 | 0 | SMF42MJBN | 8 | EBCDIC | Job name. |
| 8 | 8 | SMF42MRST | 4 | binary | Reader start time in hundredths of a second. |
| 12 | C | SMF42MRSD | 4 | packed | Reader start date in the form 0cyydddF. |
| 16 | 10 | SMF42MUID | 8 | EBCDIC | RACF® user ID. |
| 24 | 18 | SMF42MACT | 1 | EBCDIC | Activity type: A - Record added; C - Record changed; D - Record deleted. |
| 25 | 19 | SMF42MFG1 | 1 | binary | Flag 1.
|
| 26 | 1A | SMF42MCVTSFLG | 8 | binary | Virtual tape server flag. |
| 27 | 1B | SMF42MCENABLE | 8 | binary | Control record enable flag. |
| 28 | 1C | SMF42MLDTO | 8 | EBCDIC | Local time/date offset. |
| 36 | 24 | SMF42MCJNRECN | 4 | Signed | Journal record number. |
| 40 | 28 | SMF42MJNRECN | 4 | Signed | Number of next jn rec. |
| 44 | 2C | SMF42MCUPDVSI | 4 | Signed | VSI when MCUPDACT set on. |
| 48 | 30 | SMF42MCVSICNT | 4 | Signed | VSI control count. |
| 52 | 34 | SMF42MCVRLCTK | 8 | EBCDIC | VRSEL last change token. |
| 60 | 3C | SMF42MCVRSCNT | 4 | Signed | Current VRS change counter. |
| 64 | 40 | SMF42MCVRSRUN | 4 | Signed | Last HSKP VRS change counter. |
| 68 | 44 | SMF42MCSYNCTS | 8 | EBCDIC | Catsynch time stamp. |
| 68 | 44 | SMF42MCSYNCDT | 4 | EBCDIC | Catsynch date. |
| 72 | 48 | SMF42MCSYNCTM | 4 | EBCDIC | Catsynch time. |
| 76 | 4C | SMF42MEND | 0 | EBCDIC | 1st data section end. |