A figure space has the width same with as the lining numbers.
Punctuation space has the width of a period.
Flush space is a variable-width space that will change its width to fill the last line in a justified paragraph, while keeping the other spaces normal. The ID help has an example, look for "flush space".

The thin space is under Insert -> White space. So is the normal non-breaking space. Non-breaking means the two words separated by such a space won't be split in different lines.

Hope that helps!

Seb, one can include a large number of spaces into one's OpenType fonts. (I do, because it's very easy to do so, and they may be called on by people such as yourself.) The relevant Unicode page is here:
http://www.unicode.org/charts/PDF/U2000.pdf

Page three describes the various spaces, most of which travel with an accompanying dash.

The figure space should be the width of the tabular numerals in the font: useful when setting tables.
The punctuation space should be the width of basic punctuation. (In a well-built font, this means the period, comma, colon, and semicolon.)

As you mention, French setting requires a thin space preceeding "tall" punctuation: colon, semicolon, question, exclamation, etc.

How you can achieve this in InDesign, I cannot say. It would be great to have a Stylistic Set which adds that spacing for you. (This is not a difficult task.)

Gabriel & Chester,

thank you, that helps a lot. It's simpler than I thought, somehow I expected those spaces to do really triksy things.

I am haven't yet looked at OpenType, maybe because we don't use OpenType fonts at work. To be frank I don't really know what it's all about. There is so much to know these days!

Cheers

Seb

Sebastian, in InDesign CS, under 'type' you will find the option 'insert white space', and listed are em space, en space, flush space, hair space, nonbreaking space, thin space, figure space, and punctuation space. (I have the ME version, but I don't think this makes a difference.) I don't know if it depends on the font what is available--InDesign may have default widths--but in Adobe Jenson, which I am using now, there are keyboard short cuts to insert most of these spaces also.

Seb, regarding the non-breaking thin/hair spaces (which I don't believe exist) you can always use a hack such as inserting a non-breaking (word) space and reducing its width in the Character palette. I had to do something similar a while back when I was setting a book with a lot of dashes: I wanted to use thin-spaced en-dashes, but InDesign does very strange things with this sort of combination, so instead I used word-spaced em-dashes and condensed the width of the 3-part string to 65%. Normally I would never recommend glyph scaling, but in this case we're talking about characters that will not be visually distorted by doing so (blank spaces, dashes).

This is, as Hrant often says, an inelegant solution, but a solution nonetheless.

And Seb, if like me you're using InDesign in it's French version:

InDesign Menu:
Texte > Insérer une espace > Insérer une espace fine

Tu peux aussi utiliser l'espace mi-fine dans certains contextes, mon choix à ce niveau dépend surtout de la taille de caractères ou du dessin de la typo.

Non-breaking in French = Insécable

ciao ciao

Some notes from Vinnie... http://www.microsoft.com/typography/developers/fdsspec/spaces.aspx

I'm surprised more type designers don't include all the Unicode encoded spaces into their OpenType fonts - you can easily add a dozen glyphs to your total glyph count with very little work. ;-)

Cheers, Si

Simon, can you post the ratios that they showed at the Math workshop with the TeX standard spacing ratios?