DXF questions

1. am I correct in stating that a DXF code 210 can be alone, followed
by a 220, or followed by a 220 and a 230 anytime it is used?

or is it always a 2d or 3d point?

2. Common Symbol Table Group Codes
give me some examples where these would be placed.
we have both of these common codes in the same section of document,
which is really confusing, especially when placement us unclear. the
whole section is filled with symbol table entries such as VIEW, BLOCK,
APPID...

3. Common Group Codes for Symbol Table Entries
give me some examples where these would be placed.
we have both of these common codes in the same section of document,
which is really confusing, especially when placement us unclear. the
whole section is filled with symbol table entries such as VIEW, BLOCK,
APPID...

Jim Michaels

 

http://images.autodesk.com/adsk/files/acad_dxf0.pdf

Bob

 

thank you, but that doesn't answer the problem. I already have the
2009 (not the 2008) version of the document. the DXF reference is
unclear and inconsistent in this area.
it is not like a specification (which I could use), which would say
this comes before that and uses precise and consistent language. Read
it yourself and you will see what I mean. This is in the TABLES
section (4).

Can you answer the question please?
I would like to know at least 1 symbol table entry that comes after
"common group codes for symbol table entries". if someone has an
example dxf they can send me, great. I do not have Autocad, but
nonetheless I am trying to write an Autocad DXF parser.
when I say "give me an example where these would be placed" I mean
"give me an example of what symbols or group titles come after this".
I am looking for correct sequencing. How am I supposed to sequence
both of these with reference to a given symbol table entry such as
BLOCK? or is it only 1 of the 2 common groups of codes? If not, why
not?
I need help on this.

 

I have another DXF question. In a binary DXF file, what length is a
boolean (or is it a null-terminated string and has no specific
length)? what are its values?
This is not specified in the DXF ref.

 

get a copy of AutoCAD student version is not very expensive and make some
DXF files to play with.

Bob

 

hmm. this doesn't help me with the ability to parse /all/ possible
DXF file input. I have several hundred 1993-era DXF files that all
look the same. but from what I gather from the DXF format, there can
be some great variation, such as user-defined codes.

At first I thought I understood that, say, Common Group Codes for
Entities came at the beginning of every Entity, such as 3DFACE and
LINE and POLYLINE.

Then I am beginning to think that because they do not show up at the
beginning of the Entities, that it is a "pick one of these codes"
thing and that makes it a common group code.

When look at the data files, I know it can't be sequence because
directly following SEQEND is a code 8, and that's not in the list for
the 2009 Reference. Is it a mistake?