If target OS is uITRON and it has Windows compatible file system and TCP/IP which support BSD Socket, then can the developer use open, close, read, write functions for file related operation?

The developer has the options to use OS_open, OS_close, etc (OR) they can set MAP_ANSI to TRUE and have open(), close() calls map to OS Abstractor APIs. The developer also has the option to use both APIs OS_open and open() by setting the MAP_ANSI to false.