Defined in 4 files as a macro:
- contrib/ipfilter/sys/tree.h, line 279 (as a macro)
- contrib/ntp/sntp/libevent/WIN32-Code/tree.h, line 276 (as a macro)
- crypto/openssh/openbsd-compat/sys-tree.h, line 283 (as a macro)
- sys/sys/tree.h, line 281 (as a macro)