# Random Access Files

> [HTML Version](randomaccessfiles.htm)

Random access files are:

•	fixed length records containing a mixture of field types

•	ISAM and ISAM-A files are special variants of random access files

•	files must be pre-allocated; see [ALLOCATE](allocate_random.md), [CREATE](create_lit.md)

•	file expansion typically not automatic, except for ISAM, ISAM-A; see [MX\_EXPFIL](mx_expfil.md)

•	file and record locking is available; see [LOKSER](lokser_sp.md)

•	records may be "blocked" into 512 byte blocks; see [OPEN](open_random.md) statement

See [File Access Methods](fileiostatements.md) for an explanation / etymology of "Random Access".

**Subtopics**

- [ALLOCATE](allocate_random.md)

- [FILEBASE](filebase_random.md)

- [OPEN](open_random.md)

- [XOPEN](xopen_random.md)

- [READ](read.md)

- [SET'RECNO](set-recno_random.md)

- [UNLOKR](unlokr.md)

- [WRITE](write.md)

- [XREAD, XWRITE, XUNLOKR](xreadxwritexunlokr.md)