Chuck,

    The Standard Electrical Test Record in IPC 356 is used to create a bare 
board test file from CAD data or from post processed CAD data. The Alternate
Electrical Test Record is used to create a bare board test file by reading a 
IPC-D-350 formatted board description file ONLY.

    The standard electrical test and the alternate electrical test structures
are explained on page 15, paragraph 7.0.

    The standard electrical test record is fixed format...character positions
have significance. If data such as rotation of a feature is not required, then
the data fields are blank. 

    Since IPC-D-350 board description can in a variable format, the alternate
electrical test record must allow for variable formats (see paragraph 8.3.1 
which refers to paragraph 4.3.2.1 of IPC-D-350)

    The standard test record in section 7.7 describes a feature in character 
position 58 thru 71. Character positions 58 thru 62 described in paragraph 7.7.1
gives the X axis dimension of the feature to the nearest one tenthousandth.  
Paragraph 7.7.2 describes character positions 63 thru 67 which is the Y axis 
dimension of the feature to the nearest one tenthousandth. The feature described
with X and Y dimensions may be rotated as described per paragraph 7.7.3
and use character positions 68 thru 71.

    Examples of the data described in paragraph 7.7 are as follows:

    A circular land 0.050" in diameter

             Character   5 6         7
             Position    89012345678901

                         X0500Y0500

    A rectangular land 0.040" x 0.070", not rotated

             Character   5 6         7
             Position    89012345678901

                         X0400Y0700

    A rectangular land 0.040" x 0.070",  rotated 90 degrees

             Character   5 6         7
             Position    89012345678901

                         X0400Y0700R090


    Rotation has no meaning for a circular feature so character positions 68
thru 71 are not used in my first example. In the second example the rotation 
feature is not used because that feature is not rotated.

    Standard and Alternate Electrical Test files could be used in the same file,
but I wouldn't advise it. I'd use the Standard Electrical Test format 
exclusively if you are outputting the file from your CAD data.....the format's
simpler and the file size is smaller. 

    I'll send you a short sample file directly from our SCICARDS system 
formatted in IPC-D-356, Standard Electrical Test format

Harry Parkinson
IPC Gen'l Chairman, Data Format Standards     
Digital Equipment Corp
Tel 603-884-6760
FAX 603-884-1036
E-mail [log in to unmask]