Open Property Sets

What it does

A property set is a named package of fields attached to an entity of the drawing: pset.seguranca.defensa.corpo with the properties def.comprimento, def.material, and so on. It is the project's way of keeping, on the entity itself, what the geometry does not say.

The subject has two halves, and nearly every doubt comes from confusing them:

The two stores for the data

• Open Property Sets — the portable record. One record per entity, inside the entity, in a format any DWG reader understands (see The format). It needs no Object Enabler, it never becomes a proxy, and every CAD preserves it on open and save. It is the source of truth.
• The native (AEC) property set. It only exists under an Autodesk vertical. When Civil 3D is the host, every write CapCad makes is repeated in the native set, resolving the stable identifier to the style's display name. Outside Civil 3D only the portable record is written.

What holds the two together is the stable identifier. Every set and every property of the style has a var (internal, dotted, lower-case — pset.vertical.placa, def.comprimento) and a name (the name that shows in the CAD, without dots — PSET-VERTICAL-PLACA, COMP). The record always stores the var; the name is for display and for the native side. Renaming a property in the style disconnects nothing, and migration between two styles that name the same field differently works.

Workflow

1. Define the sets in the style. Property Sets tab of the Style Editor: each set's var, the name it will carry in the CAD, the list of properties with type and default value, and the rules that attach the set automatically.
2. Attach the sets to the entities. From the palette, with Add property sets...; with Apply rules, which attaches to every entity the sets whose rules match it; or automatically, when the 3D Assistant converts the drawing with Open Property Sets ticked.
3. Fill in the values. In the palette, in place; from a formula or an automatic source, with nothing to type; or in Excel, exported and imported from the palette.
4. Check. Audit... in the palette measures, for the current space, how complete the data is: which entities should carry a set and do not, and, per property, how many values are filled, empty or in error.
5. Deliver. CAPCAD_PROJECT_IFC, or the manager's IFC tab.

In Civil 3D, add one step before attaching: install the definitions in the drawing (CAPCAD_PSET_INSTALL or the manager's Install tab), so the native side has somewhere to hang the values.

The palette

CAPCAD_PSET_EDIT opens CapCad Properties, a docked palette in the shape of the CAD's own Properties window. It follows the selection: the header names the entity type and, for a block, its name; a multi-selection shows the count. Below it come the collapsible sections:

A value edited in the grid is written at once. With several entities selected, a row whose value differs between them reads *VARIES*, and an edit is written to every one of them. In Civil 3D the native set receives the same value.

Automatic and formula properties are read-only; a required property left empty is marked with *.

When the style cannot be loaded, the palette shows DEFINITIONS: DRAWING COPY and reads the set names, types and defaults from the copy the drawing keeps, so the data stays readable and editable.

The manager

CAPCAD_PSET_MANAGER opens CapCad Property Sets, modeless, reused on every run. At the top, fixed on every tab: the Active drawing: label, Style Editor..., Palette Open Property Sets and Edit definitions.... At the bottom, a log mirroring the command line and a status bar.

The other commands

CAPCAD_PSET_INSTALL — install the definitions in the drawing (Civil 3D)

Asks CapStyle path: and creates, in the drawing's native definitions, one set for each entry of the style's Property Sets section, under the name. When a set already exists it is synchronised with the style: missing properties are added and properties no longer in the style are removed, with their values. Migrate first if you renamed a property and want to keep the values.

CAPCAD_PSET_LIST — list an entity's native sets (Civil 3D)

Asks for an entity and writes, for each native set attached, one line per property in the format id, type, name = value. It reads the native side only; to see the portable record, use the palette.

CAPCAD_PROJECT_IFC — export to IFC

On AutoCAD and Civil 3D it opens the manager's IFC tab. On BricsCAD, GstarCAD, ZWCAD and ARES Commander it asks for the .ifc file and exports directly. Every entity carrying Open Property Sets data becomes an IFC 4.3 IfcSign element placed at its world position, with one IfcPropertySet per set. Properties are typed from the style: km in metres as IfcLengthMeasure, area as IfcAreaMeasure, integer and real as numbers, the rest as text; a numeric value that does not convert becomes a text label, never an invented number.

The style's vocabulary

The Style Editor offers ten canonical set categories, each tied to a CapCad column catalogue, which is where the suggested properties come from:

The vars are internal identifiers and stay as they are in every language. A set may apply to more than one category (Applies To in the editor, all for every one), and sets outside this list are accepted as custom.

Property types

text, real, integer, km, area, geographic, geographic_pair, datetime, filepath and autoincrement. On a Civil 3D installation integer and real keep their type and everything else becomes Text; the distinction stays in the style and is what the IFC export uses.

Automatic, formula, numbered and required

• Automatic: the value comes from the entity. Sources: length, area, volume, layer, handle, type, block, x, y, z.
• Formula: the value is calculated from other properties of the same entity, [Property] for this set or [Set:Property] for another, by display name or var. Arithmetic, comparison, and/or/not, text joining with &, and the functions round, floor, ceil, abs, sqrt, min, max, if, len, upper, lower, left, right, text. A formula may use another; a loop or an unknown reference stores #ERRO: reason instead of a value. A formula wins over an automatic source.
• Auto-increment: a per-drawing counter with a start and a step.
• Display format: decimals, prefix and suffix. The stored value stays raw; the format is applied when shown.
• Required: the audit counts an empty one as a defect and the palette marks it with *.

Name rules

The display name must be non-empty, at most 256 characters for a set and 64 for a property, must not start with a digit, and may use only letters, digits, _ and -. Spaces and dots are refused, which is why the name cannot be the same as the var.

The format

This section is the published format. It is what makes the sets open: anyone can read and write them with no CapCad installed.

Where the data is

Each entity that carries sets has, in its extension dictionary, an Xrecord under the key CAPCAD_PSET_MANAGER. Drawings written by earlier versions may hold it under CAPCAD_PSETS; readers should accept both, and a writer that finds the old key replaces it with the new one.

The Xrecord holds one UTF-8 JSON document, split into string values of at most 255 characters (DXF group code 1), in order. Concatenate them to recover the document. An entity with no sets has no Xrecord: removing the last set removes the record.

The document

{
  "v": 1,
  "role": "pset.vertical.placa",
  "sets": {
    "pset.vertical.placa": {
      "placa.codigo": "R-1",
      "placa.area": "3.97",
      "placa.material": ""
    },
    "catter.qto": {
      "qto.quantidade": "1"
    }
  }
}

Every value is a string, as typed or as calculated, with no display format applied: numbers use . as the decimal separator, km values are stored as typed, dates as text. Keys are case-insensitive on read and written sorted. A set with no properties is a valid empty object: the set is attached without values. Unknown keys are ignored on read.

The definitions copy

The drawing also keeps a copy of the style's Property Sets section, so the sets stay readable when the style is not at hand. It lives in the named objects dictionary, in the capcad dictionary, as an Xrecord under the key capcad.dwg.psets, chunked the same way, holding:

{
  "v": 1,
  "style": "capcad.default",
  "PropertySets": [
    {
      "var": "pset.vertical.placa",
      "name": "SINALIZACAO_VERTICAL-PLACA",
      "description": "",
      "appliesTo": ["pset.vertical.placa"],
      "appliesToTypes": ["BlockReference"],
      "appliesToLayers": ["SINA_VERT*"],
      "properties": [
        { "var": "placa.codigo", "name": "CODIGO", "description": "", "type": "text", "default": "", "required": true },
        { "var": "placa.area", "name": "AREA", "type": "area", "default": "", "auto": "area", "decimals": 2, "suffix": " m²" }
      ]
    }
  ]
}

A property carries var, name, description, type and default, and optionally sources (a map of item kind to column or fixed text), decimals, prefix, suffix, auto, formula, required, start and step. A set carries var, name, description, properties, and optionally appliesTo, appliesToTypes and appliesToLayers. The same objects, in the same shape, are the PropertySets array of a .capstyle file.

Reading it elsewhere

Any DWG library exposes extension dictionaries and Xrecords: open the entity, take the dictionary entry named above, join the strings, parse the JSON. To write, do the reverse and keep the chunks at 255 characters or less. No registration, no licence and no CapCad are needed.

Remembered between sessions

The manager remembers the last path used on each tab, the resync direction and the state of the dry-run and check-entities boxes. The palette remembers Recalculate automatically.

Notes

• The record travels with the entity. Copy, paste or WBLOCK takes it along. Because the values are stored by var and are self-contained, they stay readable in the destination drawing; the association with the definitions comes from the style active there, or from the copy the drawing keeps.
• Drawings from earlier versions are readable. Their property sets are read as they are and, on the next save, rewritten in the current form.
• CAPCAD_XDATA_CLEAN does not clean property sets. That command erases the entity's XData; the record lives in the extension dictionary, which is somewhere else. See Entities, groups and diagnostics.
• Installing synchronises by removing. Installing a style that has lost a property deletes that property from the drawing's native definitions, and with it the native values. Migrate first.
• Two routes from the Style Editor exist on AutoCAD and Civil 3D only. The Pset Manager... button and Apply to dwg send CAPCAD_PSET_MANAGER and CAPCAD_PSET_INSTALL. The Edit definitions... button of the palette works on all five CADs.