CryptoPointers

Here is another one, in the BCMA MEDICATION LOG File:

53.79,.11     ORDER REFERENCE NUMBER .1;1 FREE TEXT (Required)

              INPUT TRANSFORM:  K:$L(X)>15!($L(X)<1)!'(X?.N1"U"!
(X?.N1"V")!(X?.N1"P")) X
              LAST EDITED:      MAY 9,2001
              HELP-PROMPT:      Answer must be 1-15 characters in
length.
              DESCRIPTION:
                                Contains the IEN to the actual order
in PHARMACY PATIENT (#55) followed by a U for Unit Dose or V for IV

              RECORD INDEXES:   AORDX (#47), AUID (#147)

I call this a "crypto-pointer to the ORDER file, File 100. I recently dealt with this by creating a COMPUTED POINTER to File 100, using this field. Details on request.

BTW, a quick search of FOIA VistA finds exactly one computed pointer, field 3.3 of File 798, pointing to File 4.

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Of course the classic example is in the lab data file where a combination of PARENT FILE (.02) and NAME (,03) are used as a pseudo variable pointer to either the patient file (2) or referral patient file (67).

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And here is another one in the Domain file:

4.21,1.3        PHYSICAL LINK / DEVICE 0;5 FREE TEXT

                INPUT TRANSFORM:K:$L(X)>30!($L(X)<1) X I $D(X) S
%ZIS="NQRS",IO
                                P=X D ^%ZIS K:POP X S:$D(X) X=ION W:$D(X) "
Sto
                                red internally as ",X D ^%ZISC S IOP="HOME"
D ^
                                %ZIS K IOP,%ZIS
                LAST EDITED:    MAR 12, 1993
                HELP-PROMPT:    Answer must be 3-30 characters in length.
                DESCRIPTION:    The physical link is the channel that the
                                transmission will take place on.  This field
is
                                always a free text pointer to the device
file.
                                See field 17 / Physical Link Device for more
                                information.

Just as a historical point about the Lab Data file, that was Lab's solution for a variable pointer before at least 1986. Long before there was such a field type within FM.

Chris Edkins