French to English Tech/Engineering Computers: Hardware printed circuit boards

section heading, givingspec guidelines for advanced PCBs:
under the heading "Proximités" we've got 'proximités mécaniques', 'proximités liées à la double finition', and 'proximités liées au vernis pelable'. Maybe I'm overcomplicating the issue, but there are 'contraintes de proximité' and 'règles de proximité' too, and though we're dealing with coatings, resists and surfaces more than straight distances between components, I can't seem to find what must surely be a standard industry term (in PCb manufacture). They are indeed distances (down to microns but up to a mm), but I think..;well, let's see what you think. Packing? Close-placement? Routing/layout?
mtia