This message tells you that an IREF (Input Reference) exists in the Composer project. However, the function block cannot import it, because it is outside the scope of what it can import.
For example, if a Bus Import (AI/B, DI/B, AIL/B or DIL/B function) has a refererence in a different PCU, you will see this error. These functions can only import blocks from the same PCU, so the reference text is flawed if it in a different PCU.
Similarly, if an AI/L or DI/L import block has an IREF that exists only in another Loop, you will see this message. The reference cannot tell what is being imported, because these functions cannot import from another loop, only the same one.
--Parsing file H:\...\EBY45EB.CLD... CAD Names: 2300251A.CAD External output reference is unreachable for IREF **1AOIK CB CLSD on Module 2,30,02 Block 1652: cannot import from Loop 2 PCU 20.
Here is the actual source, as determined by the specifications.
Here is the source that the input reference indicates.
--Parsing file H:\...\EBY3DAC.CLD... CAD Names: 2320454A.CAD External output reference is unreachable for IREF L30D_MSG on Module
2,32,04 Block 1584: cannot import from Loop 2 PCU 22."
Here is the block that is being imported.
Here is the source indicated by the input reference L30D_MSG.
It is possible to see how Composer, in being robust enough to import files from WinCAD, also allows errors to persist in the input references.
This error can be built directly into Hyperview. For more information, see the article Building error reports into the M14.