Nigel -

There are numerous more specific "names" for things commonly seen in notation, but only "formally professional" musicians - or students while taking their music theory class - are likely to recognize them, even if you use them (properly).

The term "grace note" refers to how the note is typeset. Literally, it means "little note," and in French they're called "petites notes," in German "Kuz Vorschläge," in Italian "appoggiature," and "are literal reductions of full-sized note-forms, without acutal rhythmic vale in a measure, as the time in which they are to be performed must be subtracted from an adjacent beat." (see Read, cited above, p. 238)

In notation, they should be printed a little smaller than a "real" note, and single grace notes should have a "slash" through the stem, both of which indicate that their "time value" is not accounted for in the notation of the measure. Many programs let you do this much of it. The "slash" is usually omitted for multiple grace notes "attached" to the same "real note," - but there are varying opinions on this.

Most sources say that the stem always points up, unless you're notating two "voices" on the same staff, in which case grace notes for the lower voice are sometimes pointed down. Fewer programs make it easy to observe this convention, and it's probably an "optional" in the opinion of many.

If unaccented, the formal convention is that the time for the grace note should come from the preceding note. This is the most common usage, and is what most programs are "thinking" when they put in a "grace note."

If the grace note is accented, which is usually indicated by a "squashed" >, the time is taken from the following note. Many musicians in more formal forms of music use the term appogiatura for an accented grace note, and it is true that it would normally be played with a longer duration than an unaccented grace note, but modern convention is that anything that has a "full note value" should be written as a full note. Using a grace note in the notation should mean at least that it's "not quite" a standard note.

In formal music notation the "appoggiatura," while notated as a "little note" has a specific meaning - but unfortunately a different specific meaning in each of a dozen or so kinds of music. The "true appoggiature" was a construct used in medieval music that is rarely used in anything modern since it is effectively what you get with a simple accented grace note. (Whether calling an accented grace note an appoggiatua is pompous or pretentious depends entirely on whether it conveys a meaning to those to whom you speak, but to be "technically and accurately pompous and pretentious" one would have to specify that it's a "true appoggiatura," since "appoggiatura" alone has multiple meanings.)

Read reports (p 239) that "During the nineteenth century the term appoggiatura [literally "to lean"] was unfortunately confused with the term acciaccatura [literally "to crush"]. The acciaccatura is no ornament at all, but a manner of playing, then releasing part of, a chord in keyboard music. It has, then, no real connection with the ornament under consideration." (Maybe that's how we should notate mando "chunk-chunks"?)

Read includes about a page and a half of samples of the archaic appoggiatura forms, including the slide appoggiatura and the disjunct double appoggiatura but I think those would be of only academic interest here.

Many of the notation programs allow you to put in grace notes. Most of them do not play them back, so if you want them in the midi that you make from your notation, you need to go back into a copy of your notated score and "put them in as real notes," the make the midi from the "messy version."

Fewer of the cheap programs make it easy to put an accent on a grace note - and even fewer will move the accented grace note onto the beat in playback (if they play them at all). Again - make a copy and notate it fully to make the midi.

None of the above conventions can be used in "syncopated" music, where you want an "out of time" leading and accented note. Again, you write it out, or you only give your score to friends who know what your notation means.

John