#### 36.1.1 Return Values ¶

The ISO C thread specification provides the following enumeration constants for return values from functions in the API:

`thrd_timedout` ¶

  A specified time was reached without acquiring the requested resource, usually a mutex or condition variable.

`thrd_success` ¶

  The requested operation succeeded.

`thrd_busy` ¶

  The requested operation failed because a requested resource is already in use.

`thrd_error` ¶

  The requested operation failed.

`thrd_nomem` ¶

  The requested operation failed because it was unable to allocate enough memory.