Descriptor syntax

XML paths in this article refer to configuration files in the installed CAM system ($(SCHEMAS_FOLDER)), not manual attachments. Available files depend on the version and configuration.

This is the core reference chapter. It covers the XML elements, the type system, how inheritance and overriding work, and the catalog of attributes you can put on a descriptor.

1 The document skeleton

Every descriptor file is an XML document with <SCCollection> as its root element. Inside it you place namespaces, includes, type declarations and property declarations.

<?xml version="1.0" encoding="UTF-8" ?>
<SCCollection>
    <SCNameSpace ID="Operations">
        <SCInclude>$(SUPPLEMENT_FOLDER)\CommonTypes.xml</SCInclude>
        <SCType ID="TFoo" type="ComplexType"> ... </SCType>
    </SCNameSpace>
</SCCollection>

The structural elements are:

Element	Role
`SCCollection`	Document root. Always present.
`SCNameSpace`	Opens a namespace (`ID="Operations"`, `"Machines"`, …). Everything inside is declared in that namespace. May be nested.
`SCInclude`	Pulls in another file at this point. Supports `Optional="True"` and wildcards.
`SCType`	Declares a type (a reusable descriptor) — or, when nested inside another type, declares a member of it. The workhorse element.
`SCProperty`	Declares a named global property — a singleton value/object at namespace scope (see §6).

Files outside any <SCNameSpace> contribute to the namespace into which they are included — that is why CommonTypes.xml has no namespace of its own: it is included into many.

2 `SCType` — the workhorse

SCType does double duty depending on where it appears.

At the top level (or directly under a namespace) it declares a type — a named, reusable template:

<SCType ID="T2DPoint" Caption="Point" type="ComplexType">
    <SCType ID="X" Caption="X" type="Double" DefaultValue="0" DimensionKind="Linear"/>
    <SCType ID="Y" Caption="Y" type="Double" DefaultValue="0" DimensionKind="Linear"/>
</SCType>

ID is the type's name; type names its base (here the built‑in ComplexType). The nested <SCType> elements declare the type's members.

Nested inside another type an <SCType> declares a new member of the enclosing type. The member's ID is its name within the parent, and its type is the member's value type — which may be a built‑in type or any previously declared type:

<SCType ID="TSTFaceMillingOp" type="TSTMillOp">
    <!-- a member named MillingType, of the previously declared type TMillMode -->
    <SCType ID="MillingType" type="TMillMode" Caption="Milling type"/>
</SCType>

So: ID + type = "create a thing called ID that is a type", whether that "thing" is a top‑level type or a member of a complex type.

3 The type system

3.1 Built‑in (primitive) types

The type attribute accepts these built‑in names (case is not significant — Double and double are the same):

Built‑in `type`	Holds	Notes
`Boolean`	`True` / `False`
`Integer`	whole number
`Double`	real number	Use `DimensionKind` for unit handling
`String`	text
`Enumerated`	one choice from a fixed list	Items are child `SCType`s of `type="none"`
`ComplexType`	a record of named members	Children are the members
`Array`	a list of like elements	One child defines the element template; see §5
`none` (or `None`)	nothing	Used for enumeration items, separators and pure UI placeholders

Anything that is not one of these names is treated as a reference to a previously declared type — that is how composition and inheritance work.

3.2 Enumerations

An enumeration lists its options as child SCTypes with type="none". The enumeration's DefaultValue is the ID of the default option.

<SCType ID="TXYZCoordinate" Caption="XYZ Coordinate" type="Enumerated" DefaultValue="CoordX">
    <SCType ID="CoordAuto" Caption="Auto" type="none"/>
    <SCType ID="CoordX"    Caption="X"    type="none"/>
    <SCType ID="CoordY"    Caption="Y"    type="none"/>
    <SCType ID="CoordZ"    Caption="Z"    type="none"/>
</SCType>

(real example: CommonTypes.xml)

The stored value of an enum property is the option ID (e.g. CoordX), not its caption. Each option may carry its own metadata (a Caption, an ImageFile, a Priority, a Visible rule, …).

3.3 Complex types

A ComplexType is a record: its child SCTypes are its fields. Complex types can nest arbitrarily and can be reused as the type of other members.

<SCType ID="TColor" Caption="Color" type="ComplexType">
    <SCType ID="R" type="Double" DefaultValue="0.5"/>
    <SCType ID="G" type="Double" DefaultValue="0.5"/>
    <SCType ID="B" type="Double" DefaultValue="0.5"/>
</SCType>

In the inspector a TColor is rendered as a colour swatch with a picker dialog rather than three numeric rows — see §3.4.

3.4 Types with special behaviour

A handful of frequently used types are declared in CommonTypes.xml as thin aliases of a base type — you reference them by name like any declared type — but each adds extra serialization or inspector behaviour beyond its base. Declare a member with one of these when you want that behaviour:

Type	Base	What it adds
`TranslatableString`	`String`	Its value enters the localization subsystem and can be translated. By default only node `Caption`s are localized; use this type when a string value (typically a default value) must be translatable too.
`CDATAString`	`String`	Serialized inside a `CDATA` section, so the value may contain characters XML would otherwise forbid — letting it keep its original formatting, such as line breaks and tabs.
`FileName`	`String`	Holds a file path. On save/load the path is automatically converted between absolute and relative form and against path variables such as `$(SUPPLEMENT_FOLDER)`. In the inspector it offers a standard file‑open dialog; a `Filter` attribute (form `Caption (*.ext)\\|mask1;mask2`) restricts that dialog to chosen file types.
`DynamicArray`	`Array`	Behaves like an `Array` (§5), but the inspector shows the element count in the row's own value field and lets the user change it, adding or removing child elements on the fly.
`TColor`	`ComplexType`	A colour value (`R`/`G`/`B`, §3.3) rendered in the inspector as a colour swatch with a colour‑picker dialog.

(real example: CommonTypes.xml. A FileName dialog filter — the machine postprocessor field — in Machines/AbstractMachine.xml: Filter="Postprocessors (*.sppx, *.dll)|*.sppx;*.dll".)

4 Inheritance and overriding

4.1 Deriving a type

To base a new type on an existing one, name the existing type in type. The new type starts with all the members of the base and then adds the members you declare:

<SCType ID="T3DPoint" Caption="Point" type="T2DPoint">
    <!-- inherits X and Y from T2DPoint, adds Z -->
    <SCType ID="Z" type="Double" DefaultValue="0" DimensionKind="Linear"/>
</SCType>

(real example: CommonTypes.xml)

Inheritance chains can be long. A concrete operation, for instance, derives from a family of abstract operations (TSTFaceMillingOp → TSTMillOp → … → TOperationDescriptor).

4.2 Overriding an inherited member

There are two different things you can write inside a type body, and the difference is essential:

<SCType ID="Name" type="..."> — declares a new member called Name.
<Name ... /> — overrides the inherited member called Name. The tag is the member's name; you do not repeat type, you only restate the attributes you want to change.

<SCType ID="ZCleanup" type="TZCleanup" Caption="Cleanup height">
    <!-- override inherited members' defaults: -->
    <Enabled DefaultValue="True"/>
    <Height  DefaultValue="2"/>
</SCType>

(real example: Operations/MillOperations/FaceMillingOp.xml)

Overrides can reach down into nested members and even into enumeration options. The pattern <EnumItem Visible="True"/> re‑enables an option that a base type had hidden:

<CirclesDivision DefaultValue="Halves">
    <AbsQuadrants Visible="True"/>   <!-- show an option the base hid -->
    <AbsHalves    Visible="True"/>
</CirclesDivision>

(real example: Machines/AbstractMachine.xml)

4.3 Metric and inch defaults

Numeric properties can declare two defaults: DefaultValue for the metric unit system and InchDefaultValue for the imperial one. The system picks the right one according to the active unit system — they are independent values, not an automatic unit conversion, so set each to a sensible round number.

<SCType ID="Outer" type="Double" DefaultValue="0.02" InchDefaultValue="0.001"
        DimensionKind="Linear"/>

(real example: Operations/AbstractOP.xml)

5 Arrays

An Array (or the predefined DynamicArray) holds a variable number of elements of one type. You declare the element template as the array's single child:

<SCType ID="TStringList" Caption="List of strings" type="Array">
    <SCType ID="L" Caption="Line" type="String" DefaultValue=""/>
</SCType>

For arrays whose elements need a stable identity (so the application can match elements across edits), set CollectionKeyField to the name of the member that holds the key:

<SCType ID="List" type="Array" CollectionKeyField="Name">
    <SCType ID="Script" type="TScript"/>
</SCType>

(real example: Operations/AbstractOP.xml)

Inside an array element, the running index is available to expressions through Attribute(ItemIndex), which is handy for auto‑numbered captions (see the expression language):

<SCType ID="J23ValuePair" Caption="Point [Attribute(ItemIndex)]" type="TJ23ValuePair"/>

6 `SCProperty` — global named properties

While SCType declares templates, SCProperty declares a named global property: a single, addressable value or object at namespace scope. These act as shared constants/objects that expressions elsewhere can reference by name.

<SCProperty ID="MetricMeasurementsSystem" type="TMeasurementsSystem">
    <LinearUnits DefaultValue="Millimeters"/>
    <CuttingSpeedUnits DefaultValue="MetersPerMinute"/>
</SCProperty>

<!-- a computed global string that derives its value from another global -->
<SCProperty ID="LinearUnits$" type="String"
            DefaultValue="[CurrentMeasurementsSystem.LinearUnits.EnumValue.Attribute(Caption)]"/>

(real example: CommonTypes.xml)

The $ naming convention. A trailing $ in a property ID (e.g. LinearUnits$) is a convention marking a derived, display‑oriented string property. The $ is simply part of the name; it has no special parser meaning.

7 Path variables

File references — both <SCInclude> targets and attributes like ImageFile, Icon, SPPFile — use $(VARIABLE) placeholders instead of absolute paths. They resolve at runtime relative to the installation and the user profile.

Variable	Resolves to (typical)
`$(SUPPLEMENT_FOLDER)`	`<install root>\Supplement`
`$(MACHINES_FOLDER)`	per‑user `…\Machines`
`$(SCHEMAS_FOLDER)`	`$(MACHINES_FOLDER)\Schemas`
`$(OPERATIONS_FOLDER)`	per‑user `…\Operations`
`$(LOCAL_OPERATIONS_FOLDER)`	local user operations folder
`$(COMMON_CONTAINERS_FOLDER)`	shared containers/extensions folder
`$(PROGRAM_PERSONAL)`	per‑user program data

Always use these variables rather than hard‑coded paths, so your files keep working regardless of where the product is installed or which user profile is active.

8 Attribute catalog

Attributes set on SCType / SCProperty fall into two groups. A small set of core attributes is understood by the descriptor loader itself; everything else is a consumer attribute, carried along on the descriptor and interpreted by the UI, the engine, or a specific presenter. From an author's point of view both are "just attributes" — the table below tells you what each one does.

Boolean attributes take the literal text True / False (case‑insensitive).

8.1 Identity and type

Attribute	Value	Meaning
`ID`	name	The member/type name. Required on declarations.
`type` / `Type`	type name	Value type — a built‑in or a previously declared type.
`Caption`	string / expression	Human‑readable label shown in the UI. May be computed.
`Version`	integer	Schema version of the type; bump it when you change structure so older saved data is migrated.
`Obsolete`	bool	Marks a member as deprecated; kept for compatibility, generally hidden.

8.2 Values and units

Attribute	Value	Meaning
`DefaultValue`	literal / expression	Default value (metric). For enums, the default option's `ID`.
`InchDefaultValue`	literal / expression	Default value when the imperial unit system is active.
`DimensionKind`	see below	Physical dimension of a numeric value, so the UI shows units and converts correctly.
`UnitsChar`	string / expression	Explicit unit label to display (e.g. `ml/s`, or `[TimeUnits_Sec$]`).

DimensionKind values: None, Linear, InverseLinear, Angular, Feedrate, CuttingSpeed, Revolution. Use None for dimensionless numbers and direction components; Linear for distances; Angular for angles.

8.3 State and behavior

Attribute	Value	Meaning
`Enabled`	bool / expression	Whether the property is active/editable. `False` greys it out.
`Visible`	bool / expression	Whether the row is shown. Drive it from other properties for dynamic forms.
`ReadOnly`	bool	Value is displayed but not editable.
`EnabledValue`	member name	For a boolean "switch" member: names the sibling that it enables when true (used with `Compact`).
`IsStructural`	bool	Changing this value changes the object's structure (triggers a rebuild rather than a simple value update).
`IsDynamic`	bool	The member's caption/icon is computed per‑instance (e.g. array items that name themselves).

8.4 Presentation and grouping

Attribute	Value	Meaning
`Category`	category id	Assigns the property to an inspector category/tab (e.g. `TPropertiesCategoryList.Feeds`).
`Parent`	member name	Re‑parents this row under another member in the inspector tree, regardless of declaration order.
`Priority` / `Order`	integer	Sort order of a row within its inspector group/category (higher `Priority` floats up). For placement in the new operation menu, use `MultiGroup` + `OrderInGroup` instead (see Operation descriptors).
`Expanded`	bool	Whether a complex row starts expanded in the tree.
`Compact`	bool	Collapse a complex type onto a single inspector row (see §9).
`Transparent`	bool	The container itself is not shown; only its children appear (a pure grouping wrapper).
`Text`	string / expression	Summary text shown for a collapsed complex row.
`ImageFile`	path	Icon for the row (use a `$(…)` path variable).

8.5 Editors / presenters

These attributes attach a specialized editor or renderer to a property. The value is the registered name of a presenter provided by the application; you reference it, you don't define it.

Attribute	Meaning
`EnumPresenter`	Custom drop‑down/selector for the row (tool selector, magazine selector, …).
`BtnPresenter`	Renders the row as an action button (e.g. "Click to calculate").
`VisPresenter` / `CaptionPresenter`	Custom value/caption renderer.
`IsRadioEdit` / `RadioEditValue`	Combine an enum with sibling value members into one row (see §9).
`Filter` / `CustomDialogID`	For file‑name properties: file dialog filter / custom dialog.

8.6 Arrays and integration

Attribute	Meaning
`CollectionKeyField`	Member that uniquely identifies an array element.
`CollectionValueField`	Member that holds the element's payload value.
`Optional`	On `<SCInclude>`: load only if the file exists.
`ClassName` / `ClassGUID` / `InterfaceName` / `InterfaceGUID`	Bind the property to a COM object/interface the application instantiates for it. Advanced; rarely needed in hand‑authored descriptors.

Unknown attributes are preserved, not rejected. If you put an attribute the loader doesn't recognize, it is kept on the descriptor and is available to consumers and the API. That is by design — it is how presenters receive their parameters (e.g. AxisIdx, HolderType). It also means a typo in a known attribute name fails silently, so double‑check spelling and casing.

9 Compact and radio-edit rows

Two presentation patterns appear constantly in real descriptors and are worth understanding because they change how several members map to one inspector row.

Compact

Compact="True" on a complex type collapses it onto one inspector row: the first visible child is promoted next to the parent's label. The classic shape is an Enabled flag plus the value it gates, with EnabledValue linking them:

<SCType ID="SmoothCorners" type="ComplexType" Compact="True">
    <SCType ID="Enabled" type="Boolean" DefaultValue="True" EnabledValue="Radius"/>
    <SCType ID="Radius"  type="TPercentageValue" Visible="False">
        <PercentValue DefaultValue="25"/>
    </SCType>
</SCType>

(real example: Operations/MillOperations/FaceMillingOp.xml)

The user sees a single "Smooth corners" row with a checkbox and a value.

Radio edit

IsRadioEdit="True" on an enumeration merges it with sibling value members into one row, where the enum choice selects which sibling is active. Each enum option points at its sibling via RadioEditValue:

<SCType ID="ReferenceType" type="Enumerated" IsRadioEdit="True">
    <SCType ID="Angle"  Caption="(degrees)"     type="none" RadioEditValue="Angle"/>
    <SCType ID="Linear" Caption="[LinearUnits$]" type="none" RadioEditValue="Linear"/>
</SCType>
<SCType ID="Angle"  type="Double" DefaultValue="5"  Visible="False" DimensionKind="Angular"/>
<SCType ID="Linear" type="Double" DefaultValue="50" Visible="False" DimensionKind="Linear"/>

(real example: Machines/AbstractMachine.xml)

Next: Expression language

Descriptor syntax

1 The document skeleton

2 SCType — the workhorse

3 The type system

3.1 Built‑in (primitive) types

3.2 Enumerations

3.3 Complex types

3.4 Types with special behaviour

4 Inheritance and overriding

4.1 Deriving a type

4.2 Overriding an inherited member

4.3 Metric and inch defaults

5 Arrays

6 SCProperty — global named properties

7 Path variables

8 Attribute catalog

8.1 Identity and type

8.2 Values and units

8.3 State and behavior

8.4 Presentation and grouping

8.5 Editors / presenters

8.6 Arrays and integration

9 Compact and radio-edit rows

Compact

Radio edit

2 `SCType` — the workhorse

6 `SCProperty` — global named properties