s-separate-in-line - production 66

Hi everybody,

I have a question about the YAML 1.2 spec.  There is a production as follows:

[66]s-separate-in-line::=s-white+ | /* Start of line */

I can't figure out what the /* Start of line */ comment means. It
makes no sense that this production would occur only at the start of a
line.  Due to the vertical bar I'm expecting some sort of alternative,
which would mean the production means "one or more spaces or the start
of a new line"?  I'm stumped on what this production means.

Thanks.
Omari

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