OSI/AS Programming Manual

Sending and Retrieving User Data
APS Procedures Programming Concepts
2–40 056783 Tandem Computers Incorporated
Figures 2-10 through 2-12 illustrate the way in which various combinations of single
ASN.1 and octet-aligned PDV lists are unpacked from a presentation protocol data
unit (PPDU) when receiving data. Note that OSI/AS may treat adjacent PDV lists of
the same type (SAT or OCTET) and with the same PCID as a single data element.
Figure 2-10. Two Single ASN.1 User Data Elements With the Same PCID
User Data Header
Number of Elements = 1
User Data Element Header
PCID = px
Type = Single ASN.1 Type (SAT)
Length = lx + ly
User Data Element Value
PDV (lx) and PDV (ly)
APS User Data
PDV list
PCID: px
Type: SAT
Length: lx
PDV list
PCID: px
Type: SAT
Length: ly
PDV (lx)
PDV (ly)
User Data from PPDU
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