From QB64.org wiki
The UNLOCK statement opens access to parts or all of a file to other programs and network users.
UNLOCK [#]fileNumber%, record&
UNLOCK [#]fileNumber%, [firstRecord&] TO lastRecord&
- fileNumber% is the file number of the file to unlock.
- In the first syntax, the entire file is unlocked.
- In the second syntax, record& is the record number of the file to unlock.
- In the third syntax, the records or bytes in the range [firstRecord&,lastRecord&] are unlocked. If firstRecord& is omitted, it is assumed to be the first record or byte.
- For files opened in BINARY mode, each record corresponds to a single byte.
- LOCK and UNLOCK statements are always used in pairs and each statement must match the other one.
- Files must be unlocked before other programs can access them, and before the file is closed.
- Keyword Not Supported in Linux or MAC versions