How to Use BIM Tags in BricsCAD BIM

Quick answer: Two files drive BIM tagging: _SectionTag.dwg (tag block definitions and their multileader styles) and _TagTypeToStyle.xml (links BIM entity types to a multileader style each). Both live in the Support folder at C:\Users\%username%\AppData\Roaming\Bricsys\BricsCAD\V26x64\en_US\Support\Bim\Sections, confirming the same Support folder structure covered elsewhere in this hub. Run SUPPORTFOLDER and navigate to Bim > Sections to find them. Since assigning tags on a sheet also needs 3D model information, keep the 3D model open beforehand, otherwise placing the first tag can take several seconds on a large model.

How BIM Tagging Works

BIM tags are multileader entities of predefined styles that retrieve property values from the tagged BIM entities, defined two ways:

• Block content with Attributes: linework, fixed text, and attributes, each referring to a BIM property; the attribute’s content gets replaced by the actual value upon tagging.
• Text content with Fields: each field refers to a BIM property, replaced by its actual value upon tagging.

Both are stored in _SectionTag.dwg.

The first time a BIM section is placed on a new sheet, BricsCAD copies the Mleader style definitions from _SectionTag.dwg into that sheet’s DWG file; from then on, the sheet uses its own copied definitions. Running BIMTAG on a sheet also checks whether _SectionTag.dwg contains definitions not yet present in the sheet and copies those too, but it never updates definitions already copied previously (see the manual sync procedure below for that).

When you select a BIM entity to tag, BricsCAD detects its type, looks up the corresponding Mleader style name in _TagTypeToStyle.xml, finds that style’s definition in the sheet DWG, and fills its fields or attributes with the entity’s actual property values.

Editing style definitions in _SectionTag.dwg only affects tags where that block definition isn’t already present in the output drawing; editing them in a sheet DWG only affects tags in that drawing specifically.

Syncing an Outdated Style Definition in a Sheet

1. Open the sheet DWG file.
2. Delete every placed tag using that style, so it’s no longer in use in the sheet.
3. Purge the style definition from the sheet with PURGE.
4. Either update the BIM section via the context menu options in the Sheets tab of the BIM Project Browser panel, or run BIMTAG in the sheet; this copies the updated definition from _SectionTag.dwg into the sheet.

Copying Custom Styles Back into the Template

If you customized or added multileader styles in only one sheet, newly generated sheets won’t have access to them unless you copy them into _SectionTag.dwg.

1. Open both the sheet DWG containing your custom styles and _SectionTag.dwg.
2. In the sheet DWG, run MLEADERSTYLE (shortcut MLS) to open the Drawing Explorer’s Multileader Styles section.
3. Select every style you want to copy.
4. Click Copy at the top of the list.
5. In the Open Drawings tree, expand the _SectionTag.dwg node and click its Multileader Styles section.
6. Optionally delete any unneeded styles first, important: you can’t overwrite a style with the same name, so delete outdated styles before pasting new ones with matching names.
7. Click Paste.
8. Verify every desired style is now present.
9. Copy and paste their names into a text file (you’ll need these when linking BIM types to styles in the XML file).
10. Close the Drawing Explorer.
11. Save _SectionTag.dwg.

Linking Entity Types to Multileader Styles

Each code block in _TagTypeToStyle.xml follows this structure:

<tag type="BIM_ENTITY_TYPE">
  <style name="_MLeaderStyleName" autoPlacement="true" autoRotation="true" offset="1" />
</tag>

BIM_ENTITY_TYPE is BIM_ followed by the entity type’s name as shown in the Properties panel, in all caps with spaces replaced by underscores (BIM_AIR_TERMINAL_BOX for Air Terminal Box, for example). _MLeaderStyleName is the corresponding style’s name in _SectionTag.dwg. Three style options control its behaviour: autoPlacement="true" generates tags of this type automatically with the Auto option of BIMTAG (false requires manual generation); autoRotation="true" rotates the tag along the tagged entity’s main axis (false keeps it horizontal); offset="1" sets the tag’s offset perpendicular to that main axis.

1. Run SUPPORTFOLDER to open the Support folder.
2. Navigate to Bim > Sections.
3. Open _TagTypeToStyle.xml in an ASCII text editor like Notepad.
4. Add your code block at the bottom, right before </TagTypeToStyle>.
5. Save the file, then test it by creating a new sheet DWG for a BIM section and running BIMTAG on the relevant entity types.

Finding a BIM Property’s Field Expression

A multileader style’s text field stores a field expression identifying which property to display. Best practice: use a BIM model containing the entity type you’re tagging, with the desired properties (including any custom properties or block attributes) visible.

1. Open that BIM model.
2. Run FIELD to open the Field dialog.
3. In the Field names tree, go to Extensions > ExtensionProperties.
4. Click Select next to Object type and pick an entity of the type you’re creating a style for (a BIM Wall, for example); the Property category dropdown populates with every available category for that type.
5. Choose a Property category (Wall Common, for example) and then a Property (Load bearing, for example); the Field expression displays something like %<\BcObjProp Object(%<\_ObjId 2007962560>%).LoadBearing~IFC~BIM>%.
6. Copy the text starting right after the . through the last ~ segment (LoadBearing~IFC~BIM in this example) and save it to a text file, you’ll need this when customizing or creating your Mleader style.
7. Close the Field dialog.

Standard extension properties (IFC properties, for example) are also findable directly in _SectionTag.dwg or a sheet drawing, via Field names > Extensions > Object2d MLeader, though that list is very long and harder to search, making the model-based method above easier for narrower results. Custom properties specifically must use the model-based method, since they aren’t listed under _SectionTag.dwg‘s own Object2d MLeader properties until a DWG becomes part of a BIM project that actually has those custom properties set up.

Customizing an Existing Text-Content Mleader Style

1. Open _SectionTag.dwg to customize your template, or a sheet DWG to customize just that sheet.
2. Run MLEADERSTYLE (MLS) to open the Drawing Explorer’s Multileader Styles section.
3. Click a style name ending in “StyleMin” or “StyleMax” (_WallTypeStyleMin, for example).
4. Optionally edit the Leader tab’s properties.
5. Click the Content tab (Content type is set to Mtext).
6. Under Text options, click the ellipsis next to Default text; the Text Formatting toolbar opens. Dashes on a grey background represent the Field entity, replaced by the actual property value upon tagging.
7. Double-click the dashes to open the Field dialog, showing that style’s field expression, something like \BcObjProp2dMLeader Object(%<\_ObjId %MLeaderId%>%).Thickness~Quantity \f "%lu2%pr0%zs12" (in _WallTypeStyleMin‘s case, displaying the Thickness property from the Quantity property set via the Thickness~Quantity portion).
8. Replace that Thickness~Quantity portion with the string you saved earlier to change which property displays.

Creating a New Text-Content Mleader Style

1. Open _SectionTag.dwg or a specific sheet DWG.
2. Run MLEADERSTYLE (MLS) to open the Drawing Explorer.
3. Click New; the Multileader Style dialog opens.
4. Type a unique name that later identifies which entity type this style is for.
5. Under Base new Multileader Style on, choose <None> for an empty style, or an existing StyleMin/StyleMax style for example content.
6. Click Create…
7. Optionally edit the Leader tab.
8. Click the Content tab and confirm Content type is Mtext.
9. Under Text options, click the ellipsis next to Default text; the Text Formatting toolbar opens.
10. Optionally add fixed text.
11. Add a field: click Field in the Text Formatting toolbar, go to Field names > Extensions > Object2dMLeader, and select any Property from any category (Material from 3D Visualization, for example); the expression looks like \BcObjProp2dMLeader Object(%<\_ObjId %MLeaderId%>%).Material~Native.
12. Replace Material~Native with the property string you saved earlier.
13. Click OK to close the Field dialog.
14. Click OK to close the Text Formatting toolbar.
15. Close the Drawing Explorer.
16. Save the drawing.

The Block Attribute Syntax Table

A block attribute’s Tag property value uses a syntax specific to its property type, viewable in the Properties panel when an entity of that type is selected.

Customizing an Existing Block-Attribute Mleader Style

1. Open _SectionTag.dwg or a specific sheet DWG.
2. Run MLEADERSTYLE (MLS) to open the Drawing Explorer.
3. Click a style name ending in “Style” (not “StyleMin”/”StyleMax”), _WallTypeStyle, for example.
4. Optionally edit the Leader tab.
5. Click the Content tab (Content type is Block); the Source block dropdown shows the attached block, _WallTag, for example, note this name.
6. Close the Drawing Explorer.
7. Run BEDIT to open the Create or Edit Block Definition dialog.
8. Find and double-click that block to open it in the Block Editor.
9. Change the block definition freely, it can contain any geometry, text, or other elements you want displayed behind the tag’s leader line.
10. Add a block attribute that will be replaced by the actual property value: optionally copy an existing attribute or create a new one with ATTDEF (the Structure panel makes Attribute Definition entities easy to identify). Select the attribute entity in the model space, important: don’t double-click it, that opens the Edit Attribute Definition dialog, which doesn’t accept spaces in its Tag field, use the Tag field in the Properties panel instead. Type the syntax string from the table above into that Tag field, and optionally set its Text properties (Style, Justify, Height, and so on).
11. Click Close and Save in the Block Editor toolbar, or run BCLOSE with the Save option.
12. Save the file.

Creating a New Block-Attribute Mleader Style

1. Open _SectionTag.dwg or a specific sheet DWG.
2. Create a new block definition with BLOCK (build the content in model space first if you like, then convert it: choose a unique name identifying its intended style, pick an insertion point close to the geometry using Specify on-screen base point, and select Delete selected entities to remove it from the model space, keeping it only as a block definition).
3. Optionally copy another block definition in via the Drawing Explorer’s Blocks section (EXPBLOCKS or XB).
4. Run BEDIT to open the Create or Edit Block Definition dialog.
5. Edit the block definition freely.
6. Add a block attribute the same way as in the customization procedure above: optionally copy or create one with ATTDEF, select the attribute entity (never double-click it), and set its Tag field in the Properties panel using the syntax table.
7. Click Save in the Block Editor toolbar, or run BCLOSE with the Save option.
8. Run MLEADERSTYLE (MLS) to open the Drawing Explorer.
9. Click New; the Multileader Style dialog opens.
10. Type a unique name identifying which entity type this style is for.
11. Choose a source style under Base new Multileader Style on: <None> or a previously defined style.
12. Click Create…
13. Optionally edit the Leader tab.
14. Click the Content tab and confirm Content type is Block.
15. Under Block options, choose the block you just created from the Source block dropdown.
16. Close the Drawing Explorer.
17. Save the drawing.

Assigning BIM Tags Manually

The Manual option of BIMTAG lets you select exactly which BIM element to tag.

1. Open the section drawing you want to tag.
2. Choose the Manual option; you’re prompted to pick a point on a sectioned BIM element, or choose Auto, Current mleader style, or change Tag type.
3. Click a line or inside the boundary of a sectioned element (hold Ctrl to cycle through options if the point is shared between multiple entities); a tag preview appears, and you’re prompted to place it, or choose Next element.
4. Move the cursor to position it and left-click to place; you’re prompted to pick another point.
5. Repeat for every entity you want to tag (the same steps work for a floor slab or roof too).
6. Press Esc or Enter when finished.

Assigning BIM Tags Automatically

Use the Auto option to tag every BIM entity inside a viewport at once, updatable if the model changes or new elements are added.

1. Open the section drawing.
2. Launch BIMTAG; you’re prompted to select a BIM section viewport, or choose Manual or Box selection.
3. Select the viewport; since section indicators, story indicators, and grid callouts already generate automatically during a section update, you’re prompted to choose an update option: Update existing, update existing and add New, or Regenerate all.
4. Choose update existing and add New; BIM tags generate automatically for every entity in the viewport, and you’re prompted for another viewport.
5. Optionally select another viewport to tag.
6. Press Esc when finished.

Assigning Composition Tags

Composition tags specify a wall or slab’s composition, listing every ply material that makes it up.

1. Open the section drawing.
2. Launch BIMTAG; you’re prompted for a viewport.
3. Choose Manual; you’re prompted to pick a point on a sectioned element.
4. Choose change Tag type; you’re prompted to choose Tag, cOmposition, Load-bearing directions, or Spot-elevation.
5. Choose cOmposition.
6. Click a point on the element (hold Ctrl to cycle if shared between multiple entities); a preview appears, and you’re prompted to place it.
7. Move the cursor and left-click to place it.
8. Optionally repeat for more elements.
9. Press Esc or Enter when finished.

Frequently Asked Questions

What’s the difference between a Block-content and a Text-content Mleader style for BIM tags? Block-content styles use attributes inside a source block to display property values; text-content styles use fields inside plain Mtext instead.

Why doesn’t editing a style in _SectionTag.dwg update tags already placed in an existing sheet? Editing the template only affects tags where that block definition isn’t already present in the sheet; use the manual sync procedure to update an already-copied definition.

Can I display a custom property in a BIM tag? Yes, but you need to find its field expression from an actual BIM model that has that custom property set up, since custom properties aren’t listed under _SectionTag.dwg‘s own properties until a project using them exists.

What are composition tags, and how are they different from regular BIM tags? They list every ply material making up a wall or slab’s composition, chosen via the cOmposition option under change Tag type, rather than a single property value like a standard tag.