AENTR 1734 IB8S Mapping question

I have the impression I used to have the answer for this question, but I dont remember. I am copying the input data from a 1734 IB8 Safety module to a safety tag. I don't understand why there is an extra INTEGER in the destination tag, this does not make sense to me right now. Can somebody answer? See attached files. FYI, this is working I am just trying to understand why is it working, what am I missing?

module config.

Most likely the module defined data type has hidden data, most likely empty.
Whoever developed this destination UDT was trying to mimic that hidden data by inserting this integer.

Contr_Conn said:

Most likely the module defined data type has hidden data, most likely empty.
Whoever developed this destination UDT was trying to mimic that hidden data by inserting this integer.

Click to expand...

I read another post and the they were asking something similiar, and yes everybody keep talking about this hidden data type, or some reserved bytes or somethin. I just wished this was clarified somewhere by rockwell, I just havent found this piece of documentation that clarifies this. Id be so easier to understand if they just said, runmode, connection faulted, and then 2 reserved bytes, how hard was that?

As far as I know, this is done for multiple reasons, mostly to line-up data with 32-bit boundaries.
There is a UDT manual that describes how to create and use hidden data types, if you want to introduce hidden data into your UDTs.
However, copying Module defined data to an UDT is risky.
The Module defined data type can change at some point and then the revision upgrade will create issues.
Instead, the destination tag should be also Module Defined data type.
In this case it should be AB:1734_IB8S_Safety2:I:O.

No hidden data. What I said was your current module configuration is different from the what they had in the past.