pic16f628a internal oscillator setup error undefined symbol "INTOSC"
Find the appropriate #include file that your compiler is using for the particular chip you are using and look at it. That's the only way to be 100% sure what is (supposed to be) going on. 

For example, here is a snippet from a HTC include file pic16f628a.h: 

// INTOSC oscillator: CLKOUT function on RA6/OSC2/CLKOUT pin, I/O function on RA7/OS/CLKIN
#define FOSC_INTOSCCLK       0xFFFD
// INTOSC oscillator: I/O function on RA6/OSC2/CLKOUT pin, I/O function on RA7/OSC1/CLKIN
#define FOSC_INTOSCIO        0xFFFC
// EC: I/O function on RA6/OSC2/CLKOUT pin, CLKIN on RA7/OSC1/CLKIN


The constant names are sometimes changed by the compiler supplier, and you may even find errors in the files, especially for very new chips.