* Color -- the noted color is prominent in the theme in some way, whether links, text, background, or accent
* Front Page Posting -- allows you to post from the front page of your site
* Microformats -- another word for post formats
* RTL Language Support -- supports right-to-left languages
* Translation Ready -- theme supports (or has the capability to support) multiple languages

Hope that clears a few things up, at least. Thanks for your feedback! I'll pass this along to the developers for consideration next time we work on the Theme Showcase/feature filter.

The 'Color' section as a whole. What is 'white', or 'black' or 'silver' exactly - as I said in my original post "What does "White" mean in the colours? White text? White background to the text? White background to the page?" It's not obvious.

I understand the Widths section now, and Columns is easy enough. I mostly understand the Features section thanks to the tooltips I mentioned. However those tooltips are only available in the theme.wordpress.com section not in the /wp-admin/themes.php; they only exist for the Feature filters not the others, and the list is not complete there (Front Page Posting, Microformats, RTL Language Support and Translation Ready are not included).

Consequently those four would be among those I don't yet understand, altho I can guess RTL.

Also in /wp-admin/themes.php there are only three of the many Subjects visible in theme.wordpress.com, and there are none of the Styles. There are a lot of discrepancies.

As for searching for filter names in support.wordpress.com, firstly this is much more work than putting a cursor over a ? to read a tooltip or clicking the word to read a popup or link. Secondly many of the names do not lead me to a support document with further information. Colors, specific colour names, flexible width, flexible header, Translation Ready and Microformats are all examples of this.

What's more the support staff who answered my question before called flexible width 'fluid width'. There seems to be a lot of confusion even amongst staff.

Can you specify the filters you have problems with, outside of those that were already explained by @thistimethisspace?
Most filters refer to theme features that are explained in our support docs:
http://en.support.wordpress.com/

Just search for the filter you're having trouble with and it should lead you to a support document with further information.

Fluid means the width of the theme changes according to screen resolution (or the width of browser) your visitors use.

Responsive width means the the layout adapts depending on the size of the device being used to view your site. When responsive width themes are viewed on mobiles sidebars appear below the posts in order to provide as much space as possible for reading.

The WordPress.com Theme team uses the “responsive-width” tag http://theme.wordpress.com/themes/widths/responsive-width/ in the Themes Showcase to indicate which themes have this feature. http://theme.wordpress.com/themes/

There are no tooltip explanations for filters when you're searching from a new theme from the dashboard. The Help link from that Themes page doesn't mention anything about filters. Going thru to http://en.support.wordpress.com/themes/ altho there is a section on Feature Filters it does not explain what they mean. I searched with the search function for "fixed width" and "flexible width" and incredibly none of the support pages listed looked like they had an explanation of the terms, just instances of their use.

Finally by clicking thru to http://theme.wordpress.com/ which I'd not been to before I was able to find tooltips for the Features section of filters, and hence learnt that Full Width Template means you can create pages without sidebars. Still the Widths section does not have tooltips, nor any of the other sections. What does "White" mean in the colours? White text? White background to the text? White background to the page?

And incidentally these are just examples, I don't know what Responsive Layout means, or much about many of the Feature filters despite the tooltips as the information there is sparse.

Please provide explanations for *all* of the filters, and in the Manage Themes section as well as elsewhere. It should not be this difficult to work out what filters to apply to get the range of Themes we want for our blog. I have a pretty clear idea in mind in terms of layout but am not sure which to focus on due to not understanding exactly what particular named filters will mean in practice.