& is a variable separator in URL and as such, is a valid URL
character.

You may use arg_separator INI entry, like this:

arg_separator = "&"

Reopened, as the arg_separator directive is missing from
php.ini-dist / optimized and using '&' with it
does not work as the variable values get chopped.

Test script (shortest possible ;)

test.php:
<?php phpinfo();?>

And as url use something like this:

test.php?test1=12345&abcd=12345&aaa=bbbbb

BUT using ';' with arg_separator works fine
which is (AFAIK) valid too.

--Jani

And one more thing:

When using transsids, ';' works fine, but when
'&' is used, only '&' is taken of it..

--Jani

Fixed in CVS. Thanks for your report!