Per Rule Priority - prio

Introduced in OpenBSD 5.0: Per rule priority for basic shaping, priorities 0 through 7 (general default 3, others such as ssh have beefed up prio)

The Hartmeier example rewritten with prio:

pass out on $ext_if proto tcp from $ext_if set prio (3, 7)
pass in  on $ext_if proto tcp to $ext_if set prio (3,7)

as match rules:

match out on $ext_if proto tcp from $ext_if set prio (3, 7)
match in  on $ext_if proto tcp to $ext_if set prio (3, 7)

And you can sprinkle liberally across your rules. Note: default priority is 3 for most traffic