Normally, the spec refers to a step by its label,
but there are a few places where a step is referred to
by its *number*, which seems somewhat error-prone.

    2.4.4.5 "Lists of integers"
    in 'rules for parsing a list of integers',
    step 6:
        ... then return to step 4.

    12.2.3.2 "The stack of open elements"
    algorithm for 'have an element in a specific scope',
    step 4:
        ... and return to step 2.

    12.2.3.3 "The list of active formatting elements"
    algorithm for 'reconstruct the active formatting elements',
    steps 4, 6, 11:
        ... then jump to step 8.
        ... go to step 4.
        ... return to step 7.

----

For completeness, there's also:

    12.2.3.3
    alg for 'clear the list of active formatting elements ...',
    step 4:
        Go to step 1.

and

    12.2.6 "The end",
    alg for 'stops parsing',
    step 3.4:
        ... repeat these substeps again from substep 1.

but references to "[sub]step 1" are probably less error-prone.
(Likewise references to "the first/last/previous/next step".)