There is BOOL but AFAIK it actually needs more than 1 bit which makes it pretty useless if you want to save space. But you can use bits of a variable and use them as flags just like the engine does with its objects if you really need to save space:

#define FLAG1 (1<<0) // Replace FLAG1 etc. with meaningful names, these exact definitions are already in atypes.h
#define FLAG2 (1<<1)
#define FLAG3 (1<<2)
#define FLAG4 (1<<3)
#define FLAG5 (1<<4)
#define FLAG6 (1<<5)
#define FLAG7 (1<<6)
#define FLAG8 (1<<7)

...

long a_var;

...

a_var |= FLAG1; // set first bit/flag to 1
a_var &= ~FLAG1; // set first bit/flag to 0