Named Alternative Group Object

CDXML Name:altgroup
CDX Constant Name:kCDXObj_NamedAlternativeGroup
CDX Constant Value:0x800A
Contained by objects:kCDXObj_Page, kCDXObj_Group
First written/read in:ChemDraw 4.0


A NamedAlternativeGroup is a container object holding fragments that represent alternative substituents for a query. It should contain two or more fragments and/or groups containing fragments. The optional property kCDXProp_NamedAlternativeGroup_Valence (1 if not present) describes the number of external connection points. Each fragment or group must contain exactly that number of external connection point nodes. Generally, there will be a Node in another fragment not contained in this NamedAlternativeGroup which has Node_Type equal to kCDXNodeType_NamedAlternativeGroup, and a kCDXProp_Node_AltGroupID property that refers to this NamedAlternativeGroup object.

The number of bonds connected to a named alternative group node should match the valence (number of external connection points in each fragment) of the alternative group. If a named alternative group node has more than one bond connected to it, the named alternative group node should contain a kCDXProp_BondOrdering property.

A NamedAlternativeGroup is also commonly known as an R-Group or a G-Group.

A NamedAlternativeGroup must contain a Text object, and a NamedAlternativeGroup without any contained fragments is pretty useless. It has no required properties.

Value Name CDXML Name
0x8002 kCDXObj_Group group
A logical collection of objects.
0x8003 kCDXObj_Fragment fragment
A collection of nodes and their connectivity (bonds).
0x8006 kCDXObj_Text t
An arbitrary block of (possibly styled) text.
0x8011 kCDXObj_ObjectTag objecttag
Arbitrarily named property, one or more of which can be attached to any ChemDraw object.

Value Name CDXML Name Type
n/a n/a id UINT16
A unique identifier for an object, used when other objects refer to it.
0x000A kCDXProp_ZOrder Z INT16
Back-to-front ordering index in 2D drawing.
0x000F kCDXProp_IgnoreWarnings IgnoreWarnings CDXBooleanImplied
Signifies whether chemical warnings should be suppressed on this object.
0x0010 kCDXProp_ChemicalWarning Warning CDXString
A warning concerning possible chemical problems with this object.
0x0011 kCDXProp_Visible Visible CDXBoolean
The object is visible if non-zero.
0x0204 kCDXProp_BoundingBox BoundingBox CDXRectangle
The smallest rectangle that encloses the graphical representation of the object.
0x0301 kCDXProp_ForegroundColor color UINT16
The foreground color of an object represented as the two-based index into the object's color table.
0x0302 kCDXProp_BackgroundColor bgcolor INT16
The background color of an object represented as the two-based index into the object's color table.
0x0B00 kCDXProp_NamedAlternativeGroup_TextFrame TextFrame CDXRectangle
The bounding box of upper portion of the Named Alternative Group, containing the name of the group.
0x0B01 kCDXProp_NamedAlternativeGroup_GroupFrame GroupFrame CDXRectangle
The bounding box of the lower portion of the Named Alternative Group, containing the definition of the group.
0x0B02 kCDXProp_NamedAlternativeGroup_Valence Valence INT16
The number of attachment points in each alternative in a named alternative group.


CDX Documentation index