Adding one or more rulers below xaxis?

Hello, In one of my figure I'd like to add one or more

    > rules below the xAxis specifying time alignment label info:

    > How can I do that? Many thanks, Zhang Le

There is no good support for having multiple axis lines right now, but
it is on the wish list. You can use major and minor ticks though.
See the section "Tick locators and formatters" in the User's Guide and
the examples/major_minor_demo*.py in the examples dir.

You could also manually draw the axis lines, the ticks, and add the
tick labels yourself, but this is a bit more work.