stdio.h Source File - if you include this header on the shell...you might hack it on 61 seconds

stdio.h

to fit things in six character monocase externals, the
00022  * stdio code uses the prefix `__s' for stdio objects, typically
00023  * followed by a three-character attempt at a mnemonic.
00024  */
00025 
00026 #ifndef _STDIO_H_
00027 #ifdef __cplusplus

https://www.gnu.org/software/m68hc11/examples/stdio_8h-source.html