What is a redline markup?
A redline markup is an annotation layered over a drawing to flag an error or request a change. It triggers a revision without altering the released file, so the correction is recorded against the drawing while the released version stays intact.
The name comes from the red pen once used to mark corrections on a printed sheet. The markup is the request, not the fix. The fix arrives as the next revision.
How a redline works for an asset owner.
A redline starts when a reviewer, a surveyor, or a maintenance crew finds something on a drawing that is wrong or needs to change. Rather than editing the released sheet, they draw the correction over it as a markup: a cloud around the area, a note, a dimension to fix. That markup flags the change and triggers a revision, so the drawing is put right on the record while the released version stays untouched until a new revision is issued.
For an asset owner, redlines are how a correction is raised without anyone quietly changing a controlled drawing. The released sheet stays the released sheet. The markup sits against it as the request, and the revision that follows is the fix, so the record shows what was flagged, and what was done about it.
Read how CAD drawing redlines workHow Lunr handles redline markups.
When a drawing is uploaded to Lunr, a PDF rendition is generated so the sheet can be viewed in the browser and marked up on the web, without a CAD licence. Markups are stored securely against that rendition, and access is controlled by securities: read-only users typically see only the latest as-constructed drawing, not the markups. When a drawing is released from a document workflow, the markups stay with the version they were made on, so the new as-constructed version does not carry the previous version's redlines.
Related reading.
How redline markups work on CAD drawings, from project revisions to on-site maintenance, and what triggers each one.
How a document moves from draft to released, and what happens to the markups when a new version is issued.
Configure the states, actions, and transitions a document moves through, so a flagged change advances only when it is approved.
The practice of keeping every version of a drawing on the record, with one revision marked current.
Questions about redline markups.
- What is the difference between a redline and a revision?
- A redline is the markup that flags a change on a drawing. A revision is the new version of the drawing that carries the change once it is made. The redline is the request, drawn over the released sheet without altering it, and the revision is the fix, issued as its own version. One triggers the other, so the record shows both what was flagged and what was done about it.
- Does a redline change the released drawing?
- No. A redline markup sits over the released drawing as an annotation, so the released file itself is not altered. The correction it asks for is made in a new revision, which is issued as its own version. Until that revision is released, the released sheet stays exactly as it was issued.
- Who can create and see redline markups?
- Access to redline markups is controlled by securities. Typically only authorised users can view and create them, while read-only users see the latest as-constructed drawing rather than the markups. That keeps the review process controlled and keeps the released drawing clean for anyone building from it.
Mark up drawings in the browser, on the record.
Book a walkthrough with someone who knows what a transmittal and an as-constructed drawing are, and watch Lunr keep redlines, revisions, and the released file straight.
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