In a message template, outside a table the string '{MyOid.errors}' is replaced by '#ERRORONLY#' if the colour of MyOid is green. The documentation specifies that "If the value assigned to a data alias is green, then the value that replaces this flag (that is, flag errors) will be blank." The attached patch causes Devmon to behave as documented.
There is a related and undocumented feature in Devmon. If a line contains only someting like '{MyOid.errors}' and the colour of MyOid is green, the text '{MyOid.errors}' is replaced by an empty string and additionally, the newline following it is suppressed. After including the attached patch, this feature is still available.
In the transition from Linux to Windows, the line endings have disappeared. Attached is the same patch, however now with Windows line endings.
It is found that after applying the patch above, the behaviour in case the colour is yellow or red is not as documented. Attached is the improved patch.