This slug is reserved for use by another page ?

Question

When trying to use "1" to use as category slug I receive an error !

Which category slugs are allowed and which are not allowed ?

FOr title, which characters . () [] , - _ are not allowed ?

Thank You

Answer 1

It's because numbers are reserved for questions. A question URL is of the form /qa/123 so you can't have a category "123" because the category should be at /qa/123 also.

I assume that any letter in there would be fine, or any punctuation mark not listed above.

Comments

You are right, adding a c1, c2 is fully sufficient... I know it is not the nicest for seo, but as I have 3 levels only the last one has a nice slug, so urls do not become too long.