Greetings to Renoise team!
Here’s a new command of mine: Trill!
Trill xy, precisely. Where x denotes the number of semitones to the upper note and y is, naturally, its speed! What do you say to that?
Sincerely,
Artur 
What if you want to trill starting downwards instead of upwards?
Can’t this be achieved through current DXX, UXX & VXX pattern commands?
Post an example of a trill sound?
Hm, shift x so that 7 or 8 are the base note, below is below, above is above?
But I think trills, and grace notes, do really live from a certain timing variance or unevenness. I experimented with lpb16 and FF speed glide commands, such ornamentations sound crap when sequenced in pure even tempo. Fiddling with note delays can make them sound musical again. Arpeggio can be “abused” for such, but lacks configurability, and depends hard on bpm/lpb/tpl settings. One byte of data for such commands just isn’t enough to make them powerful.
Post an example of a trill sound?
Quite a few audio examples on the Wikipedia page:
http://en.wikipedia.org/wiki/Trill_(music)
In general, I do think this is an interesting idea for a command, but when considering how the commands currently work, I somehow doubt that we could ever squeeze enough musical flexbility into the x and y digits.
If x was the number of semitones, and y was a combination of speed and direction — ie. y 0 to 7 = trill upwards, y 8 to f = trill downwards — then it might roughly work, but it would still be incredibly limited overall, and I suspect that such limitations would only lead to frustration.
It’s a similar situation with arp command — it’s a lot of fun in theory, but terribly limited in practise, and only really useful in somewhat rare situations.
Overall, I’d say you’re better off simply programming these things directly in the pattern editor itself. The only really limiting factor there is your chosen Lines Per Beat setting, and how much notation you can comfortably squeeze into a few pattern lines. Nevertheless, you could quite easily use phrases to contain some high LPB trill patterns, then map the phrases to an unused octave within the instrument. That way you can play your regular notes easily within the pattern editor, then drop in a trill phrase whenever you need the extra articulation. If you get really creative with it, your phrase could even contain maYbe commands to add random variations in note velocity, delay, etc., to give a more organic sound. Just an idea anyway 
Quite a few audio examples on the Wikipedia page:
http://en.wikipedia.org/wiki/Trill_(music)
thnx, thought it was a pitch vibrato thing.
the way I create such sounds with samples right now is through the ‘extend iterate’ processes in the CDP tool. Takes little fiddling getting the right parameter settings and pretty flexible with the randomization options.