Understanding command lines.

Hello

I'm working on modifying Marlin 1.1.0-RC6 to work with 2 extruders and 1 nozzle.

I have found the following code in my pins_RAMPS_24.h file.

#if MB(RAMPS_14_SF) || MB(RAMPS_13_SF) || ENABLED(IS_RAMPS_EFB)

#define HEATER_1_PIN -1

#else

#define HEATER_1_PIN 9 // EXTRUDER 2 (FAN On Sprinter) was pin 9

#endif


I can only find 3 places in my project where "ENABLED(IS_RAMPS_EFB)" is referenced.
Once when it is defined and twice where it is check by "IF" statements.
The way I'm reading this is : IF "enabled(is_ramps_efb" has been "Enabled" then execuite
"Define HEATER_1_PIN as -1 .

This is apparently the case since I get an error message when compiling saying that heater_1_pin is not defined.

Since I've never found a place that "enables" "is_ramps_efb" it makes me wonder if I am missing something?

thank you

kd6hq