I created %ZSTART, having just learned about it. I included some minimal code to test it, as follows:
%ZSTART
SYSTEM
WRITE "SYSTEM.",!
QUIT
JOB
WRITE "JOB.",!
QUIT
LOGIN
WRITE "LOGIN.",!
QUIT
CALLIN
WRITE "CALLIN.",!
QUIT

Now Terminal still works as normal, and sure enough I get "LOGIN" displayed, but when I start Studio I get an error message such as the following. I wonder what Caché ODBC has to do with it.

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Receiving HL7 messages from our EMR, and processing to send out to downstream system. These are SIU_S12 messages, with a custom ZOR segment added by the EMR to include order information. The purpose of including this segment is to allow us to only send messages to the vendor that contain a procedure ID that is included on the list of procedures desired by the vendor. These values are in a LUT with the procedure ID in the key field, and a value of 1.

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