just for nicer appearance in SED (compiled well, but the bracket opening "{" is handled by the text editor as if a real code bracket open), I use ascii codes instead of strings:

//#define obrackets file_str_write (wmb_handle,"{")
//#define cbrackets file_str_write (wmb_handle,"}")
#define obrackets file_asc_write(wmb_handle,123)
#define cbrackets file_asc_write(wmb_handle,125)