If a composite glyph is made out of glyph members that all contain anchors meant to position the individual glyph members, then Auto Attach positions the members for you and keeps them positioned when the members change. Right-click one or more glyphs in the Font Overview, or right-click in the glyph editor, and select Auto Attach > Enable. The anchors themselves can be placed by hand or with Set Anchors.

The order of the glyph members is important, as mark glyphs must come right after a base glyph. If the base glyph is not the first one, then select it, right-click, and select Order > Bring to Front. Alternatively select Custom Formula from the Glyph menu, to adjust the order of the glyph members through the formula.

If your glyph is a ligature with marks, do ensure the Glyph OpenType Type as available on the Glyph Properties panel is set to Ligature and has the correct amount of ligature components.

Placement

Auto Attach owns the position of a member, and nothing else. Each member has a placement mode, set from the glyph editor's right-click Placement submenu next to Auto Attach; one click sets it on every master, with undo:

•Automatic - Auto Attach controls X and Y. The default, and what an accented letter needs. The member cannot be dragged.

•Automatic Horizontal - Auto Attach controls X; the vertical position you gave the member is kept. This is the mode for superscripts and inferiors built from one shared figure: author each height, and let the horizontal placement stay automatic. The member drags vertically only.

•Manual - Auto Attach does not move the member. It drags freely.

The modes are kept with the glyph: switching Auto Attach off and on does not reset them, and a newly added member starts as Automatic.

Design parameters per master

A member's scale, transform and smart component values are yours and are kept per master; Auto Attach maps its anchor math through them instead of resetting them. Only the structure of the composite (which members, in which order) follows the default master. Advances follow as well: a member scaled to 60% contributes 60% of its advance, and a smart component member contributes the advance of its resolved shape, so the host's advance width and side-bearings stay right when a member changes size. A member that is a smart component attaches to its anchors as resolved at the member's smart coordinates, so dialling a smart axis moves the attachment point with the shape.

Marks attach on the side the character calls for, not on the side the mark glyph happens to be drawn for, so one mark shape can serve two positions.