Is there a page in the documentation that describes what's a "PHP-standardized" version number?

Wrong test script was provided. Right one:
var_dump(version_compare('2.1.0-DEV', '2.1.0-dev', '<'));

hmm, you can strtolower before compare, I'd prefer this to be a doc problem..

>Is there a page in the documentation that describes what's a "PHP-standardized" 
version number?
The description block gives a fairly precise explanation for how version numbers 
are compared: after a couple character replacements, numeric parts are compared 
as numbers and non-numeric parts (eg, "alpha" and "rc") are compared according 
to a hierarchy.

>hmm, you can strtolower before compare, I'd prefer this to be a doc problem..
The operator parameter says "This parameter is case-sensitive, so values should 
be lowercase". Maybe move that somewhere more obvious, like the description or a 
note?

Yes, definitely, because without third parameter result is the same:
var_dump(version_compare('2.1.0-DEV', '2.1.0-dev'));
var_dump(version_compare('2.1.0-dev', '2.1.0-dev'));

int(-1)
int(0)

And this: "This parameter is case-sensitive, so values should 
be lowercase". is probably about the parameter itself:
var_dump(version_compare('2.1.0-dev', '2.1.0-dev', 'lt'));
var_dump(version_compare('2.1.0-dev', '2.1.0-dev', 'LT'));

bool(false)
NULL

This bug has been fixed in the documentation's XML sources. Since the
online and downloadable versions of the documentation need some time
to get updated, we would like to ask you to be a bit patient.

Thank you for the report, and for helping us make our documentation better.

Thank you aharvey!
I was going to propose to change it to something like this
```
Special version strings such as <literal>alpha</literal> and   	     <literal>beta</literal> should be lowercase. Otherwise they will be treated as
<literal>any string not found in this list</literal>.
```
but after a test it turned out that it's not working that way:
var_dump(version_compare('2.1.0-DEV', '2.1.0-dev', '<'));
var_dump(version_compare('2.1.0-ALPHA', '2.1.0-dev', '<'));
var_dump(version_compare('2.1.0-BETA', '2.1.0-dev', '<'));
var_dump(version_compare('2.1.0-RC', '2.1.0-dev', '<'));

bool(true)
bool(true)
bool(true)
bool(false)

Actually it's working that way, I forget that "RC = rc".