How to Use Centre Lines and Centre Marks in BricsCAD

Quick answer: Centre lines and centre marks are reference entities marking axes of symmetry and the centres of circular openings. Both are associative, updating automatically whenever the lines, circles, or arcs they reference are modified.

Worth noting: this source documents a distinct command family, CENTERLINE and CENTERMARK, and never once mentions DIMCENTER, the command referenced on the Dimensioning Tools Overview page elsewhere in this hub. These appear to be two genuinely separate approaches rather than the same command under different names, DIMCENTER for a simpler center mark, and CENTERLINE/CENTERMARK for this fully associative version.

The Centre Line and Centre Mark Commands

Command	What it does
`CENTERLINE`	Creates a centreline entity, associated with two selected lines
`CENTERMARK`	Creates a centre mark entity, associated with a selected circle or arc
`CENTERREASSOCIATE`	Recreates the association between a centreline and two lines, or a centre mark and a circle or arc
`CENTERDISASSOCIATE`	Breaks the association of a centreline or centre mark entity
`CENTERRESET`	Resets centreline and centre mark entities

System Variables for Centre Entities

Variable	Controls
`CENTERCROSSGAP`	The gap between a centre mark and its centrelines. Type a value for an absolute size in drawing units, or a value followed by `x` for a size relative to the circle or arc’s diameter (the default, `0.05x`, creates a gap 5% of the diameter). A single `.` creates no gap at all
`CENTERCROSSSIZE`	The size of the associative centre mark. Type a value for an absolute size in drawing units, or a value followed by `x` for a size relative to the diameter (the default, `0.1x`, creates centre marks 10% of the diameter). A single `.` creates zero-length centre mark lines
`CENTEREXE`	The length of centreline extensions, in drawing units
`CENTERLAYER`	The default layer for new centrelines and centre marks. Type a name (created automatically if it doesn’t exist yet), or a single `.` to use the current layer instead
`CENTERLTYPEFILE`	The linetype file used for centrelines and centre marks: `default.lin` by default in imperial drawings, `iso.lin` in metric ones, the same file-splitting pattern used for regular linetypes and hatch patterns elsewhere in this hub
`CENTERLTYPE`	The linetype for new centrelines and centre marks. Type a name, press Enter to keep the current one, or type a single `.` for a continuous line
`CENTERLTSCALE`	The linetype scale for new centrelines and centre marks
`CENTERMARKEXE`	Whether centrelines automatically extend for new centre marks or not

Editing Centre Entities

Edit their properties directly in the Properties panel.

Frequently Asked Questions

Is CENTERLINE the same command as DIMCENTER? This source doesn’t say so, and never mentions DIMCENTER at all. They appear to be two separate approaches, with CENTERLINE/CENTERMARK being the fully associative version documented here.

What happens to a centreline if I move one of the lines it’s associated with? It updates automatically, since centrelines and centre marks are associative entities.

How do I control how large a centre mark appears relative to its circle? Set CENTERCROSSSIZE to a value followed by x for a size relative to the diameter, the default is 0.1x, 10% of the diameter.

Can I break a centreline’s association with its lines without deleting it? Yes, run CENTERDISASSOCIATE. Use CENTERREASSOCIATE afterward if you want to reconnect it.