Naming of any of four vertexes presented on the picture gives Compound of vertexes instead of a single vertex

Selection of a single Vertex (any of four vertexes presented on the picture)
from the built shape returns Compound of vertexes. It is limitation of the
current Naming algorithm implementation. Theoretically the case has solution.
Script to reproduce the problem (Naming testing framework to be used):

NewDocument D MDTV-Standard
AddDriver D Box Cyl Sph Attach XAttach PTxyz PTALine PRLine PMirr Cut

#0000001 Create Box
NewCommand D
set B2 [AddObject D]; ## add object
set F2 [AddFunction D $B2 Box]; ## add function
BoxDX D $B2 190; ## set arguments of this function
BoxDY D $B2 290
BoxDZ D $B2 390
InitLogBook D; ## initialize (clean) internal maps of labels
ComputeFun D $F2; ## compute the function
GetShape D $F2:2 Box2; ## check result

#0000002 Create Cylinder
NewCommand D
explode Box2 F
explode Box2_1 E
set Sel1 [AttachShape D Box2_1_1 ${B2} ${B2} 1]; ## set attachment
## AddDriver D Attach Cyl
set Cyl [AddCyl D 70 275 ${Sel1}]
ComputeFun D $Cyl:1
GetShape D $Cyl:1:2 CylS

#3 Transalte Cylinder
NewCommand D
set FTr1 [PTranslateDXYZ D $Cyl 100 0 0]
ComputeFun D $FTr1
GetShape D $Cyl:2:2 CylS

#4 Cut Box Cylinder
NewCommand D
set CS [AddCut D $B2 $Cyl]
ComputeFun D $CS
erase
GetShape D $CS:2 S
don S

#5 Naming
NewCommand D
explode S V
set Sel5 [AttachShape D S_5 ${B2} ${B2} 0];
set Sel6 [AttachShape D S_6 ${B2} ${B2} 0];
set Sel7 [AttachShape D S_7 ${B2} ${B2} 0];
set Sel8 [AttachShape D S_8 ${B2} ${B2} 0];


============================================
scripts creates at the label specified by each selection Naming data structure
which defines compound of Vertexes. Algorithm should be refined for case when
Selection shape in Filter is a Vertex.