Dear All
Can you please let me know what does this declaration means?
'_far const char'
Thank you

Can you give some context, I'm not sure.
Maybe you ment const char _far;?

Sorry, Its exact declaration is as :
_far const char cmd_clr_scr[] = {27,'[','2','J',0};
Please help me.

I'm really not sure what _far does, but from the context I'd say it's some preprocessor definition somewhere in the source code.

As for the rest const char cmd_cls_scr[] = {27,'[','2','J',0};, this creates a constant character array called cmd_cls_src and assigns it the 5 characters you see there (note: 27 will be whatever ASCII value 27 is, and 0 is the null terminating character you find at the end of c-strings i.e. '\0')