According to doc of ultraplot.subplots (or ultraplot.Figure), there are four levels of axis sharing.

• 0 or False: No axis sharing. This also sets the default spanx and spany values to False.

• 1 or 'labels' or 'labs': Only draw axis labels on the bottommost row or leftmost column of subplots. Tick labels still appear on every subplot.

• 2 or 'limits' or 'lims': As above but force the axis limits, scales, and tick locations to be identical. Tick labels still appear on every subplot.

• 3 or True: As above but only show the tick labels on the bottommost row and leftmost column of subplots.

• 4 or 'all': As above but also share the axis limits, scales, and tick locations between subplots not in the same row or column.

However, I found that ultraplot does not respect this convention exactly in ultraplot=1.60.2.
For example, share=1, share="labs", share=labels do not provide the expected behavior (though these options do provide identical results).
Here is a minimum example:

%matplotlib
import ultraplot as uplt
fig, axs = uplt.subplots(None, 2, 3, sharey='labels')
axs.format(ylabel='PDF')

fig, axs = uplt.subplots(None, 2, 3, sharey='labs')
axs.format(ylabel='PDF')

fig, axs = uplt.subplots(None, 2, 3, sharey=1)
axs.format(ylabel='PDF')

In contrast, ultraplot=1.50 works as expected (left panels in screenshot below).

However, interestingly, I notice that the example in userguide using uplt.figure works as expected.
So there seems an inconsistency between uplt.subplots and Figure.subplots?

BTW, also note that in the user guide, point 3 does not provide the full list of the five available options (compare to proplot), though it says "five" just above the list.
Is this change intentional or a misoperation?