This message means that the input reference refers to a module that is not the one indicated by the module specification (S1) in an AIL/B or DIL/B function.
--Parsing file E:\...\RI_UNI~4\EBY1E5C.CLD... Module 8 for IREF MILL GROUP F IN SERVICE~ (S3) does not match module 0 (S2) in file -- skipping. Module 4 for IREF ANY W.U. VLV IN SERVICE~ (S3) does not match module 2 (S2) in file -- skipping. Module 4 for IREF EF ANY IGN OR W.U. TRIPPED~ (S4) does not match module 2 (S2) in file -- skipping.
Looking at the logic, you can see that what has happened is that an unused DI/L block has been put on a boneyard sheet. The natural outputs, blocks 813 and 814, are not used anywhere else.
When you run into a DBDOC error message of this type, it makes sense to get rid of the offending text eventually in a safe, effective manner. In this Composer case, the reference text should be deleted, which would make the messages go away.
This error can be built directly into Hyperview. For more information, see the article Building error reports into the M14.