When you create a new integer field type, there is an "Authorized input" parameter to limit to only a specific perl expression. No need for additional plugins.

OK, I have created an installable decimal field type plugin that creates a double MySQL data type. It has a maximum and minimum limit like the integer field type and another parameter that allows you do define how many decimal places you can have.

It seems to be working very well and I am happy to upload it to the forum if anyone is interested. Or better I could add it to the directory if I can be granted access.

I have submitted it to the directory and you can download it here:

www.joomlapolis.com/component/option,com_mtree/task,viewlink/link_id,391/Itemid,55/

Feel free to post comments or suggestions.

Nice...

... but when I use it as a search-field I get this error:
[code:1]Notice: cbSqlQueryPart::_sqlQuoteValueType: ERROR_UNKNOWN_TYPE: const:double in /home/xxxxxxxx/administrator/components/com_comprofiler/plugin.class.php on line 2441[/code:1]

Do I have to change plugin.class.php ?

But you aren't going to tell anyone how to access it, are you Nick!