Granting user webservd the permission to create a subdirectory of a directory owned by bob. Note that webservd won't be able to remove this subdirectory unless he's also granted D permission on the parent directory or gives himself d permission on his subdirectory.
webservd@box-01:/home/bob/dir1 $ mkdir subdir1
mkdir: Failed to make directory "subdir1"; Permission denied
bob@box-01:~ $ chmod A+user:webservd:rxpaRcs:allow dir1
bob@box-01:~ $ ll -dV dir1
drwxr-xr-x+ 2 bob staff 2 Jun 20 08:11 dir1
user:webservd:r-xp--a-R-c--s:-------:allow
owner@:rwxp-DaARWcCos:-------:allow
group@:r-x---a-R-c--s:-------:allow
everyone@:r-x---a-R-c--s:-------:allow
webservd@box-01:/home/bob/dir1 $ mkdir subdir1
webservd@box-01:/home/bob/dir1 $ ll -dV subdir1
drwxr-xr-x 2 webservd webservd 2 Jun 20 08:23 subdir1
owner@:rwxp-DaARWcCos:-------:allow
group@:r-x---a-R-c--s:-------:allow
everyone@:r-x---a-R-c--s:-------:allow
webservd@box-01:/home/bob/dir1 $ rmdir subdir1
rmdir: directory "subdir1": Search or write permission needed
webservd@box-01:/home/bob/dir1 $ rm -r subdir1
rm: Unable to remove directory subdir1/: Permission denied
bob@box-01:~ $ chmod A0=user:webservd:rxpDaRcs:allow dir1
bob@box-01:~ $ ll -dV dir1
drwxr-xr-x+ 3 bob staff 3 Jun 20 08:23 dir1
user:webservd:r-xp-Da-R-c--s:-------:allow
owner@:rwxp-DaARWcCos:-------:allow
group@:r-x---a-R-c--s:-------:allow
everyone@:r-x---a-R-c--s:-------:allow
webservd@box-01:/home/bob/dir1 $ rmdir subdir1
webservd@box-01:/home/bob/dir1 $ ll
total 0
bob@box-01:~ $ chmod A0=user:webservd:rxpdaRcs:allow dir1
bob@box-01:~ $ ll -dV dir1
drwxr-xr-x+ 3 bob staff 3 Jun 20 08:35 dir1
user:webservd:r-xpd-a-R-c--s:-------:allow
owner@:rwxp-DaARWcCos:-------:allow
group@:r-x---a-R-c--s:-------:allow
everyone@:r-x---a-R-c--s:-------:allow
webservd@box-01:/home/bob/dir1 $ mkdir subdir2
webservd@box-01:/home/bob/dir1 $ rmdir subdir2
rmdir: directory "subdir2": Search or write permission needed
bob@box-01:~ $ chmod A0=user:webservd:rxpaRcs:allow dir1
bob@box-01:~ $ ll -dV dir1
drwxr-xr-x+ 3 bob staff 3 Jun 20 08:35 dir1
user:webservd:r-xp--a-R-c--s:-------:allow
owner@:rwxp-DaARWcCos:-------:allow
group@:r-x---a-R-c--s:-------:allow
everyone@:r-x---a-R-c--s:-------:allow
bob@box-01:~ $ ll -dV dir1/subdir2
drwxr-xr-x 2 webservd webservd 2 Jun 20 08:35 dir1/subdir2
owner@:rwxp-DaARWcCos:-------:allow
group@:r-x---a-R-c--s:-------:allow
everyone@:r-x---a-R-c--s:-------:allow
bob@box-01:~ $ chmod A0=owner@:rwxpdDaARWcCos:allow dir1/subdir2
chmod: ERROR: Failed to set ACL: Not owner
bob@box-01:~ $ chmod A+user:webservd:rxdaRcs:allow dir1/subdir2
chmod: ERROR: Failed to set ACL: Not owner
webservd@box-01:/home/bob/dir1 $ chmod A0=owner@:rwxpdDaARWcCos:allow subdir2
webservd@box-01:/home/bob/dir1 $ ll -dV subdir2
drwxr-xr-x+ 2 webservd webservd 2 Jun 20 08:35 subdir2
owner@:rwxpdDaARWcCos:-------:allow
group@:r-x---a-R-c--s:-------:allow
everyone@:r-x---a-R-c--s:-------:allow
webservd@box-01:/home/bob/dir1 $ rmdir subdir1
webservd@box-01:/home/bob/dir1 $ ll
total 0
