Octavo has several different kinds of margins, each with a different colour. Once you understand what each one does, the placement model makes a lot of sense — but it can be a bit overwhelming at first. This page explains how Octavo thinks about placing content, and why.
Octavo works with a simple one-to-one model: one source page goes onto one destination page. You can’t arrange multiple source pages on a single destination page like you would in a DTP program — that’s not what Octavo is for.
The imposition style you’ve chosen (saddle stitch, tri-fold, etc.) may put multiple destination pages onto one physical sheet of paper, but Octavo still thinks of each one as a separate page. One source page maps to one imposed page.
So placement is really about one question: how does a single source page get positioned within its destination page?
Think of placement as a series of nested rectangles, from the outside in:
This is the physical piece of paper. Its size comes from your media settings.
The red shaded area around the edges represents the area your printer can’t reach. These margins don’t affect placement at all — Octavo places content as if the whole sheet were available. The red shading is purely a warning: if your content extends into this area, it won’t print. You might not care (e.g., if you’re trimming the sheet anyway).
If you’ve set a trim size, this is the area of the sheet you’ll keep after cutting. If you’re using the whole media (no trimming), then the trim zone is the whole sheet.
This is the destination page — the rectangle that your source page will be placed within. Outside of the trim zone, the only things Octavo will render are bleed and printer’s Source Page.
The blue margins, set in the Source Page tab, define which part of the source page you care about. Everything within the blue margins is the content that gets placed; everything outside is ignored (unless bleed is involved — see below).
The purple margins, set in the Placement tab, define where your source content will be positioned within the trim zone. These are your output margins — the gap between the edge of the page and where the content goes.
If the placement margins are zero, content is placed right up to the edge of the trim zone.
Octavo takes the content inside the blue source margins and fits it into the area inside the purple placement margins. The Content Scaling and Content Position settings in the Placement tab control exactly how.
If the source content is smaller than the placement area, the position control (the 3×3 grid) determines where it sits. If it’s larger, scaling brings it down to fit.
That’s the core of placement. Everything else is refinement.
Bleed is where things get more nuanced. Octavo’s bleed model is more flexible than what you might be used to from other apps — see the Bleed page for the full explanation. But the short version: