question on identifiers

In the lesson on java identifiers , i see that the below mentioned identifier is considered illegal , but not sure why ? I mean - it seemed to follow the rules .

int e#_couut;

Is it because '#' is not a unicode character ? Is there a chart some where that lists all the allowed values that can be used in an identifier name ?

Is there a chart some where that lists all the allowed values that can be used in an identifier name ?

Yes, not a chart, but an explanation, here.

Thank you Christophe . The link was helpful.

The convention is that identifiers should begin with a letter (Upper-case for class/interface/enum names, lower-case for everything else) and then contain letters and numbers only. $_ are permitted by the compiler, but should be avoided.
The exceptions are:

Package names may contain underscores _ and may begin with underscore (see this Java™ Tutorials section) and are lower-case throughout

Constant identifiers (public static final) are UPPER_CASE throughout with words separated by underscores

You will see identifiers beginning with $; those names are added automatically by compilers.

Thank you for the explanation, Campbell.

You're welcome

But surely you mean "Christophe and Campbell"?

Yes

...Thanks to both of you.