Openings, rooms and layers covers recording a door and reading net. This page is what happens after the line is already on the sheet: the length is an object you keep editing, not a bundle you have to redraw.
Continue a length
Select a length and press L. Click near either end to carry on from there. Click near a vertex in the middle to start a new part of the same measurement, a T into the wall. The drawer footer reads Adding to, with the name and the net, the same way a count already names the row the next marker joins.
Finish with a double-click, Enter, or a right-click. Right-click also finishes a polygon that has enough corners. Escape cancels the points you just added and leaves the row as it was.
Snap and join
While you are tracing, endpoints and vertices of other lengths on this page pull the cursor in. The targeted run's segments snap too. Hold Shift first if you want a 45 degree bearing; the snap still wins after that.
When a finished run shares a point with another length, you are offered Join into the survivor, with the other row leaving its group. Join keeps one measurement. Keep separate leaves two. Selecting two lengths and pressing J, or using Join on the palette, joins them even when they do not touch: they become parts of one row.
Split and detach
Select an interior vertex and press X, or Split here on the palette. The chain under that vertex becomes two rows. The new one is named with a 2, in the same group and colour. An opening centred exactly on the split stays with the original.
Detach part, E, moves one whole part onto its own row. It is the inverse of joining a T. A run with only one part cannot detach.
Vertices and segments
Under Move, the midpoint handles insert a vertex, as they always have. Insert vertex on the palette arms the next click on a segment. Delete a vertex or a segment from the palette or with Delete when that part is selected. Deleting a middle segment of a length leaves two parts on the same row. An area cannot lose a segment, because opening the ring would not be an area anymore, and it cannot drop below three corners.
Openings stay put
A door is recorded on a part of the wall, not as a point on the page. When you insert a vertex, drag one, join two runs, or split one, the door stays over the same printed symbol. If you delete the segment it sat on, the opening goes with it, and the notice says so. Undo brings both back.
Thickness and which face you traced
The palette's Wall section sets thickness in inches and whether you traced the centre, the left face or the right face. Left and right follow the direction you drew. This changes the band on the canvas and the three offset lengths the palette shows. It never changes the linear result, the group total, or a mapped item's quantity.
A garage traced around the outside of a 20 by 24 printed box often reads a bit over 91 feet against a printed 88. With thickness 6 inches and Reference side Right (the outside), the palette reads traced 91.27, centreline 89.27, other face 87.27. A true 21 by 25 outside rectangle at 6 inches reads 92 outside, 90 on centre, 88 inside: each half-thickness step loses 8 times the offset, which is why the 88 is the inside face. Ordering both faces of drywall is still Multiplier 2; the hint on that field says so.
Plot all walls
Plot all walls is already under AI assist: Detect walls on this page (free), or Ask AI for walls. Each piece it lands is an ordinary length, so you can join adjacent pieces, give a piece the right face and thickness, and keep editing it like any other run. Detect still misses windows sitting inside the wall line; add those by hand.
One marker of a count
Under Move, click one count marker to select that instance alone. The row reads how many of the total are selected. Delete removes only those markers. The drawer row still selects the whole set. A Shift-drag on empty canvas draws a box around several markers at once; a plain drag still pans, which the phone needs.
This is not a substitute for your judgment. Read the sheet.