HelenOS sources

isspace            82 common/stdc/ctype.c int isspace(int c)
isspace            82 kernel/generic/common/stdc/ctype.c int isspace(int c)
isspace           109 kernel/generic/include/macros.h #define isspace(c) \
isspace            82 uspace/lib/c/common/stdc/ctype.c int isspace(int c)
isspace            61 uspace/lib/cpp/include/__bits/locale/locale_misc.hpp     bool isspace(Char c, const locale& loc)