In an orchestral score I am working on I have noticed that the space size shown in the layout cards of the parts (1.7mm) differs from that shown in layout options (1.75mm). For the full score layout, on the other hand, the layout card and the layout options agree (1.2mm).
Possibly relevant:
(1) I set the space size for the full score myself, while the parts are defaulted.
(2) The project was imported via xml from Sibelius.
A cursory experiment (using a few native Dorico projects and layouts) indicates that the layout card rounds to the nearest .1
I’m not entirely sure what the rules are for which direction it rounds (up or down) but I can’t imagine it’s anything more sinister than this.
Thanks pianoleo. I don’t think it’s sinister either, but I did find it confusing!
I agree we should show the size to the same level of precision for each measurement unit between the Layout Options dialog and the layout card. We’ll change this in future.
My question is related (although maybe this isn’t the best post to ask in). When the preference is set for inches, the precision of adjustment in space size changes hugely with each click of the up or down adjustment chevron (it appears to be about 0.1" increments). If I begin with a Rastral Size 4 (space size 0.064") and click the DOWN chevron once, it goes to 0". If I start with Size 4 and click the UP chevron once, it goes to 0.16" – a huge jump in size. Those adjustment buttons are useless with such huge changes in size; I have to manually type in the numbers to make appropriate changes.
Can the resolution be set to adjust by 0.001" instead? That would be much more useful.
This has been discussed before. Surely moving in thousandth of an inch increments is way too small to be useful?
I find it useful in making adjustments to get two systems that almost fit on a page to fit. More often I find that two systems may overlap (I know it’s not supposed to but it does); making the tiniest adjustment in size will often cure that issue, while not reducing legibility in a noticeable fashion. I’ve also used it to reduce say 8 1/2 pages to 8 (along with reducing note spacing). Slight adjustments are very useful for my purposes.
The problem is that the possible units are very different in size, and Dorico doesn’t compensate for that very well.
For example looking at staff spacing in Engrave mode, the distances are displayed either to 0.1pt (which is not too different from a thousandth of an inch) and the spin controls increment by 1pt, or 0.1 inch with an increment or 0.1inch which is nearly 10 times bigger.
The “obvious” answer is just delete inch units - after all, they are only used by one country, and the other 97% of the world population wouldn’t miss them at all 
I will review the step size for the various units in the multi-unit spin box and see about making them smaller for centimetres and inches.