File Locking Levels

#define SQLITE_LOCK_NONE          0
#define SQLITE_LOCK_SHARED        1
#define SQLITE_LOCK_RESERVED      2
#define SQLITE_LOCK_PENDING       3
#define SQLITE_LOCK_EXCLUSIVE     4

SQLite uses one of these integer values as the second argument to calls it makes to the xLock() and xUnlock() methods of an sqlite3_io_methods object.

See also lists of Objects, Constants, and Functions.

SQLite is in the Public Domain.
https://sqlite.org/c3ref/c_lock_exclusive.html