The errors are system dependent. In SunOS 4.0, there are 89 defined UNIX system call errors.
Success:
        % the following sample errors are for SunOS 4.0
      errno_id(1,M).  (gives M = "Not owner").
      errno_id(2,M).  (gives M = "No such file or directory").
      errno_id(3,M).  (gives M = "No such process").
      errno_id(4,M).  (gives M = "Interrupted system call").
      errno_id(5,M).  (gives M = "I/O error").
      errno_id(6,M).  (gives M = "No such device or address").
      errno_id(89,M). (gives M = "Remote address changed").
      errno_id(90,M). (gives M = "Unknown system error").
        % the latter occurs for all errors greater than 89.
Error:
      errno_id(N,M).         (Error 4).
      errno_id(1.0,M).       (Error 5).
      errno_id(1,"message"). (Error 5).