If you are using #DTrace on #FreeBSD, then I've got good news for you.
I've added a new manual to FreeBSD. It's called d(7) and it is a short reference of the #D scripting language. Currently, it covers only a subset of all variables and functions, but we'll add more iteratively.
Here are some previews for you:
HTML: https://people.freebsd.org/~0mp/d.7.html
MDOC (view with man(1)): https://people.freebsd.org/~0mp/d.7
Have fun tracing your systems!