The attached patch adds a new type of "special_constraints" to graphics properties (only row vector properties for now). I don't really like the name. But it pretty much describes what it can be used for: Adding constraints to properties that need "some special" check.
For now it adds the constraint "ENFORCE_ASCENDING" to the [xyz]tick and [xyz]lim properties of axes.
It can also be used to add other constraints in the future: e.g. the "position" (and related) properties should allow only non-negative values in the third and fourth element while there should be no such limitation on the first and second element...

I am not sure whether it makes sense to also integrate the (mutually exclusive) "finite_constraints" into these new (accumulative) "special_constraints".

I didn't find any properties that must be strictly decreasing. I just added that case to check whether the enumeration works as expected. If you think it is better to remove that case from the patch, I don't mind at all.

(file #42451)

I also think it is reasonable to expect increasing values.  I think that this catches a common case where a user mistypes or otherwise accidentally specifies a strange sequence of values.

If they really do have a strange sequence, it isn't a burden for them to sort those before passing to the plotting code.

Yes, I think it is reasonable to expect ticks to be increasing values.

When setting manual axis ticks, Octave allows them in any order. Matlab throws the following error if they are not ascending:

semilogy(0.1:0.1:7)
set(gca, 'ytick', [10 3 1 0.3 0.1], 'ylim', [0.02 17], 'yminorgrid', 'on')
Error using matlab.graphics.axis.Axes/set
While setting the 'YTick' property of 'Axes':
Value must be a vector of type single or double whose values increase

While that could be a nice extension to the Matlab syntax, it might lead to unexpected behavior: e.g. the minor grid lines outside the major tick range are not shown (see bug #52376). There might be also other side effects.

Should we follow Matlab here and force the manual ticks to being in ascending order?