AutoCAD VB.net Programming with DXFCODEs

Over the last couple of weeks I've been working with the code for the January 2011 release of DrawOrder by Layer for AutoCAD on the Autodesk Labs Plugin of the month page which can be found here. The code uses a selection filter via the DXFCODE protocol to find the layer names matching the strings in the list generated from the block table record. I am currently revising this command to add some additional items and will post it once it is complete. Here is what the code looks like to select objects on the selected layer:

For Each lay As String In revLst
Dim psr As PromptSelectionResult
Dim tvs(0) As TypedValue
tvs(0) = New TypedValue(DxfCode.LayerName, lay)
Dim sf As New SelectionFilter(tvs)
psr = ed.SelectAll(sf)
If psr.Value IsNot Nothing Then
dot.MoveToTop(New ObjectIdCollection(psr.Value.GetObjectIds))
End If
pm.MeterProgress()
System.Windows.Forms.Application.DoEvents()
Next

While doing this I have been looking through the DXFCODE format codes in VB.net and have been trying to find a list of what these all do and what they are for. I found a pretty good list here, also displayed below in relation to the {}Autodesk.AutoCAD.DatabaseServices namespace. Note that these are in order by the group code and not alphabetical.

DXFCODE Group Names, Codes, and Descriptions

Group Name	Group Code	Description
Invalid	-9999
XDictionary	-6
PReactors	-5	APP: persistent reactor chain
Operator	-4	APP: conditional operator (used only with ssget)
FirstEntityId, XDataStart	-3	APP: extended data (XDATA) sentinel (fixed)
Header	-2	APP: entity name reference (fixed)
End	-1	APP: entity name. The name changes each time a drawing is opened. It is never saved (fixed)
Start	0	Text string indicating the entity type (fixed)
Text, XRefPath	1	Primary text value for an entity
AttributeTag, BlockName, MlineStyleName, ShapeName, SymbolTableName, SymbolTableRecordName	2	Name (attribute tag, block name, and so on)
AttributePrompt, CLShapeName, Description, DimensionAlternativePrefixSuffix, DimPostString, DimStyleName, LinetypeProse, SymbolTableRecordComments, TextBigFontFile, TextFontFile	3-4	Other text or name values
DimensionBlock, Handle	5	Entity handle; text string of up to 16 hexadecimal digits (fixed)
DimBlk1, LinetypeName	6	Linetype name (fixed)
DimBlk2, TextStyleName	7	Text style name (fixed)
LayerName	8	Layer name (fixed)
CLShapeText	9	DXF: variable name identifier (used only in HEADER section of the DXF file)
XCoordinate	10	Primary point; this is the start point of a line or text entity, center of a circle, and so on DXF: X value of the primary point (followed by Y and Z value codes 20 and 30 APP: 3D point (list of three reals)
YCoordinate	20	DXF: Y values of the primary point
ZCoordinate	30	DXF: Z values of the primary point
Elevation	38	DXF: entity's elevation if nonzero
Thickness	39	Entity's thickness if nonzero (fixed)
PixelScale, Real, ShapeScale, ShapeXOffset, ShapeYOffset, TxtSize, TxtStylePSize, TxtStyleXScale, ViewBackClip, ViewFrontClip, ViewHeight, ViewLensLength, ViewportAspect, ViewportHeight,ViewWidth,	40-48	Floating-point values (text height, scale factors, and so on)
LinetypeScale	48	Linetype scale; floating-point scalar value; default value is defined for all entity types
DashLength, LinetypeElement, MlineOffset	49	Repeated floating-point value. Multiple 49 groups may appear in one entity for variable-length tables (such as the dash lengths in the LTYPE table). A 7x group always appears before the first 49 group to specify the table length
Angle, ViewportSnapAngle, ViewportTwist	50-58	Angles (output in degrees to DXF files and radians through AutoLISP and ObjectARX applications)
Visibility	60	Entity visibility; integer value; absence or 0 indicates visibility; 1 indicates invisibility
LayerLinetype	61	Layer Linetype
Color	62	Color number (fixed)
HasSubentities	66	"Entities follow" flag (fixed)
ViewportVisibility	67	Space-that is, model or paper space (fixed)
ViewportActive	68	APP: identifies whether viewport is on but fully off screen; is not active or is off
ViewportNumber	69	APP: viewport identification number
CircleSides, Int16, LinetypeAlign, LinetypePdc, RegAppFlags, TxtStyleFlags, ViewMode, ViewportGrid, ViewportIcon, ViewportSnap, ViewportSnapPair, ViewportSnapStyle, ViewportZoom	70-78	Integer values, such as repeat counts, flag bits, or modes
Int32	90-99	32-bit integer values
Subclass	100	Subclass data marker (with derived class name as a string). Required for all objects and entity classes that are derived from another concrete class. The subclass data marker segregates data defined by different classes in the inheritance chain for the same object. This is in addition to the requirement for DXF names for each distinct concrete class derived from ObjectARX (see "Subclass Markers")
EmbeddedObjectStart	101
ControlString	102	Control string, followed by "{" or "}". Similar to the xdata 1002 group code, except that when the string begins with "{", it can be followed by an arbitrary string whose interpretation is up to the application. The only other control string allowed is "}" as a group terminator. AutoCAD does not interpret these strings except during drawing audit operations. They are for application use
DimVarHandle	105	Object handle for DIMVAR symbol table entry
UcsOrg	110
UcsOrientationX	111
UcsOrientationY	112
XReal	140
ViewBrightness	141
ViewContrast	142
Int64	160	64-bit integer values
XInt16	170	16-bit integer values
NormalX	210	Extrusion direction (fixed)DXF: X value of extrusion direction APP: 3D extrusion direction vector
NormalY	220	DXF: Y values of the extrusion direction
NormalY	230	DXF: Z values of the extrusion direction
XXInt16	270
Int8	280	8-bit integer values
RenderMode	281
Bool	290-299	Boolean flag value
XTextString	300-309	Arbitrary text strings
BinaryChunk	310-319	Arbitrary binary chunks with same representation and limits as 1004 group codes: hexadecimal strings of up to 254 characters represent data chunks of up to 127 bytes
ArbitraryHandle	320-329	Arbitrary object handles; handle values that are taken "as is." They are not translated during INSERT and XREF operations
SoftPointerId	330-339	Soft-pointer handle; arbitrary soft pointers to other objects within same DXF file or drawing. Translated during INSERT and XREF operations
HardPointerId	340-349	Hard-pointer handle; arbitrary hard pointers to other objects within same DXF file or drawing. Translated during INSERT and XREF operations
SoftOwnershipId	350-359	Soft-owner handle; arbitrary soft ownership links to other objects within same DXF file or drawing. Translated during INSERT and XREF operations
HardOwnershipId	360-369	Hard-owner handle; arbitrary hard ownership links to other objects within same DXF file or drawing. Translated during INSERT and XREF operations
LineWeight	370-379	Lineweight enum value (AcDb::LineWeight). Stored and moved around as a short. Custom non-entity objects may use the full range, but entity classes only use 371-379 DXF group codes in their representation, because AutoCAD and AutoLISP both always assume a 370 group code is the entity's lineweight. This allows 370 to behave like other "common" entity fields.
PlotStyleNameType	380-389	PlotStyleName type enum (AcDb::PlotStyleNameType). Stored and moved around as a short. Custom non-entity objects may use the full range, but entity classes only use 381-389 DXF group codes in their representation, for the same reason as the Lineweight range above.
PlotStyleNameId	390-399	String representing handle value of the PlotStyleName object, basically a hard pointer, but has a different range to make backward compatibility easier to deal with. Stored and moved around as an Object ID (a handle in DXF files) and a special type in AutoLISP. Custom non-entity objects may use the full range, but entity classes only use 391-399 DXF group codes in their representation, for the same reason as the Lineweight range above.
ExtendedInt16	400-409	16-bit Integers
LayoutName	410-419	String
ColorRGB	420
ColorName	430
Alpha	440
GradientObjectType	450
GradientPatType	451
GradientTintType	452
GradientColCount	453
GradientAngle	460
GradientShift	461
GradientTintVal	462
GradientColVal	463
GradientName	470
Comment	999	DXF: The 999 group code indicates that the line following it is a comment string. SAVEAS does not include such groups in a DXF output file, but OPEN honors them and ignores the comments. You can use the 999 group to include comments in a DXF file that you've edited
ExtendedDataAsciiString	1000	ASCII string (up to 255 bytes long) in extended data
ExtendedDataRegAppName	1001	Registered application name (ASCII string up to 31 bytes long) for extended data
ExtendedDataControlString	1002	Extended data control string ("{"or "}")
ExtendedDataLayerName	1003	Extended data layer name
ExtendedDataBinaryChunk	1004	Chunk of bytes (up to 127 bytes long) in extended data
ExtendedDataHandle	1005	Entity handle in extended data; text string of up to 16 hexadecimal digits
ExtendedDataXCoordinate	1010	A point in extended data DXF: X value (followed by 1020 and 1030 groups) APP: 3D point
ExtendedDataWorldXCoordinate	1011	A 3D world space position in extended data DXF: X value (followed by 1021 and 1031 groups) APP: 3D point
ExtendedDataWorldXDisp	1012	A 3D world space displacement in extended data DXF: X value (followed by 1022 and 1032 groups) APP: 3D vector
ExtendedDataWorldXDir	1013	A 3D world space direction in extended data. DXF: X value (followed by 1022 and 1032 groups) APP: 3D vector
ExtendedDataYCoordinate	1020	DXF: Y and Z values of a point
ExtendedDataWorldYCoordinate	1021	DXF: Y and Z values of a world space position
ExtendedDataWorldYDisp	1022	DXF: Y and Z values of a world space displacement
ExtendedDataWorldYDir	1023	DXF: Y and Z values of a world space direction
ExtendedDataZCoordinate	1030	DXF: Y and Z values of a point
ExtendedDataWorldZCoordinate	1031	DXF: Y and Z values of a world space position
ExtendedDataWorldZDisp	1032	DXF: Y and Z values of a world space displacement
ExtendedDataWorldZDir	1033	DXF: Y and Z values of a world space direction
ExtendedDataReal	1040	Extended data floating-point value
ExtendedDataDist	1041	Extended data distance value
ExtendedDataScale	1042	Extended data scale factor
ExtendedDataInteger16	1070	Extended data 16-bit signed integer
ExtendedDataInteger32	1071	Extended data 32-bit signed long