Hi again:
Terry, for a 'refresher' on some of the considerations of working with FS9 land class Vector Textured Polygons (aka "VTP") and the VTP layering scheme, you might wish to take another look at the info addressed in another thread wherein we discussed Compton Abbas:
http://www.fsdeveloper.com/forum/threads/tutorial.426486/
NOTE: The
internal layer number of a VTP BGL is a separate binary attribute (stored inside the BGL) and is distinct from the priority number associated with a BGLs physical position within the FS9 Scenery Library GUI stack of layers.
http://www.fsdeveloper.com/forum/showpost.php?p=639049&postcount=2
Of particular note might be the link to Luis Feliz-Tirado's excellent tutorial "
Ground2K for Beginners", which addresses working with various FS9 terrain vector line and polygon land class textures as well as "vector
excludes" ...within the context of the FS VTP layer numbering system (which IIUC, still applies regardless of whether one uses G2K, ADE, SBuilder etc. to make this particular type of terrain scenery):
http://library.avsim.net/search.php?SearchTerm=Ground2K for Beginners&CatID=root&Go=Search
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Also to be considered is the info within the original
Ground2K4 for FS9 manual "
Ground2K4_US.doc" in:
Ground2K4 V5.1
http://library.avsim.net/download.php?DLID=39207
...and other documents within 5 "official" updates / patches released by author Christian Fumey:
Ground24K V5.30
http://library.avsim.net/download.php?DLID=41110
Ground2K4 V5.32
http://library.avsim.net/download.php?DLID=41426
Patch Ground2K4 V5.33
http://library.avsim.net/download.php?DLID=45391
Ground2K4 V5.40
http://library.avsim.net/download.php?DLID=58600
Patch Ground2K4 V5.6
http://library.avsim.net/download.php?DLID=87880
Of course, the above are supplements to numerous references for VTP scenery found in the
SBuilder for FS9 help file via:
SBuilderX Menu > Help > [Search Tab] > Search String: "VTP" click 'List Topics' > [click topic title] > (
topic shows in right window pane)
And then we have Holger's modifications of the "default" VTP layering scheme:
http://forum.avsim.net/topic/79970-sbuilder-201-blns-and-missing-airport-masksvtp-layer/
Additionally, whether one makes terrain scenery content for a airport area via
ex: ADE, AFX, SBuilder etc., one may need to be certain that any BGLComp-compiled XML exclude "rectangles" utilized (these are distinct from VTP excludes !

) at /near an airport scenery do
not have an "
Exclude All" attribute where one wishes to allow FS9 autogen trees to be displayed normally.
IIUC, this caveat would apply regardless of whether that autogen is to be displayed on default land class texture 'tiles' used in default mode, with custom VTP polygons which use default land class 'textures', or on custom resample-generated photoreal land class scenery with autogen Annotations applied via *an.agn files in the local paired \Texture folder.
In airport creation / modification, one might find it appropriate to
use a number of small BGLComp-compiled XML exclude rectangles with specific locally-needed exclude attributes rather than 1 large exclude rectangle which excludes "all" ...as discussed here:
http://www.fsdeveloper.com/forum/threads/autogen-exclude-trouble.21467/
http://www.fsdeveloper.com/forum/th...-autogen-trees-oddly-enough-it-worked.113508/
...and as explained in detail by Jim Vile's excellent tutorial here in the context of FSX airport modification:
http://www.fsdeveloper.com/forum/threads/landclass-visibility-problem.15173/
BTW: Of incidental note is Scott Smart's explanation of FS9 Airport Background texture polygons being implemented by ACES via use of VTP2 land class polygons (which are duplicates of the default airport flatten poly, and which utilize default land class textures # 1182 through 1200 that are also
designed to remove autogen) ...on VTP layer 7:
http://www.fsdeveloper.com/forum/threads/autogen-exclude-trouble.21467/#post-142154
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Hope this might help with better understanding some quirks of the FS VTP (internal) layering system with regard to excludes.
GaryGB