It's not clear what you're trying to do that is causing difficulty. Typically, there is nothing to do... the fact that GDL interprets numeric lengths internally as meters isn't something that anyone usually needs to pay attention to.
For example, if your Working Units are meters and your parameter A is the chair dimension you want to be 450mm, then you would enter 0.45 for that parameter in the object settings dialog. If your Working Units are millimeters, you would enter 450. When the parameter is passed to the object script, the conversion is performed to meters. Same if an Imperial Units user entered 1'-6" in the object settings dialog (or in the script) ... that would be converted to meters if you were to examine the value received in the object script (0.4572 m).
If you are hard-coding your chair to be 450mm, then you would enter 0.45 in your script.
In case this isn't clear yet (I'm tired), let's say you have a parameter in your object that defaults to 450mm (so you would have entered it as 0.45 since values are meters inside your script). In the Object Setting dialog, if your working units are set to mm, that parameter will appear as 450. If you working units are meters, it will appear as 0.450.
One of the forum moderators • AC 26 USA and earlier • macOS Ventura 13.2, iMac Pro 10-Core, Radeon Pro Vega 64
One should mention that in the GDL editor's parameter list you can have two types, that look similar, but behave differently.
One is the length parameter, the other is the "natural number" parameter. Both are represented as floats, so it is not obvious in how they differ.
However, the natural number parameter will stay the same no matter the working unit; the length parameter on the other hand will itself present differently to the user – depending on what working unit is set.
Mostly AC 26 on Mac | Author of SelfGDL | Developer of the GDL plugin for Sublime Text | «Furthermore, I consider that Carth... yearly releases must be destroyed»