【转帖】section views

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section views
have looked for the answer to this question in several drafting text books, although not in the ansi standards. is it required that section views be identified in sequence (a,b,c...) or can a letter be skipped. i had a drawing with several section views, a through f, and decided to delete c.
i was told that i would need to rename all of the sections that appeared after c. not that it was difficult to do, especialy with solidworks.i have never heard of this requirement before. is this really a necessary?
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i believe it is only required that view letter names be unique.  i've had drawings where section a-a gets removed but section b-b remains.  i leave the lettering as it was so viewers familiar with the drawing will know b-b is still b-b, and it was a-a that was removed.
some places i've seen skip letters "i" and "o" in drawing names.  yes, some drawings do get that big.
customer satisfaction, while theoretically possible, is neither guaranteed nor statistically likely.--e.l. kersten
thanks for the reply. most places that i have worked (in new york) would not use the letters i, o, q, u, or v. especially for eco's. here in pennsylvania the two companies i have worked for use all the letters on both drawings and eco.
also, letters are to be used once. for example, if you have datums a, b & c, your section views will start with d-d, e-e, etc. and the other way ... sect a-a, b-b ... datums c, d, etc. this has been standard drafting practice.
can't use letters i,o,q,s,x & z.
while i have seen company standards which forbid the use of the same letters for view callouts and datums, it is not an industry standard.  modern drafting practices and standards manual, published by genium, is based on the asme specifications, and states (para 4.3.1) "gdt datums on the drawing can have the same letters as the views... but not i, o, q, s, x, or z."  
thanks ewh, i will read it.
as for the letter designations for views, sections, etc., the trend i have seen is that any new drawing should use letter designations in an uninterrupted alphabetic order (excluding i, o, q,...).
you can have a view a and a section a-a and a datum a all in the same drawing because these are all distinctly different drawing entities.  if a drawing gets so busy that z is reached, then you move on to double letters e.g. aa.
as the drawing is changed to add and remove sections, views, datums, etc. it's ok to leave a gap in the sequences.  there certainly are no hard and fast industry-wide rules or standards that say that the gaps have to be filled! in fact, to reduce on errors, it's best to just move on to the next available letter.
the same goes with reference designators for electronic equipment; a new assy should have no gaps in reference designators.  as the design is revised it is expected that gaps will appear as parts are designed in or designed out.  it is certainly a fruitless exercise to fill in these gaps as the design changes.  in fact, efforts to fill in those gaps has screwed up many a schematic, bom, silkscreen, and assembly drawing!
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it seems to me nowdays drawings go to the fab shop pritty much and shamfully unchecked. it happens where i work. we just dont seem to have the time. this trend should be resisted by all.
on to the point of this thread. in school it was always emphicised to me that a drawing is like a map and if someone looked at it and got lost, well it needed to be changed. if it isnt clear how can they build it. using a, aa or a1,etc will add clarity to the interpertation then that is allowed.
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pennpoint      
another possible solution is to go to the section you omit, simply line through it with a notation that section c-c has been replaced by section #-# (as appropriate) and ask the client if that is acceptable.  for lengthier drawings, this is  less time consuming and communicates the same info to the reader.
if the drawings are computerized into a gis, national cad stds may be appropriate. see aia/csi/a/e/c cadd stds.  also iso 13567 layering standards.
we often delete a section or view and
leave the other section or views as before.  
we simply state removed sec aa in the
revision.  it is too expensive to change
all of the views, sections, etc. just
because you delete one of these.  the
same applies to datums.