Result off nodata function

[Jarne St]

Hello,
This is just a quick question to confirm that I understand the nodata() function correct.

I try to create a trigger if I receive data from an SNMP Trap.
Because the data() function don't exists I have to use "no nodata()".

This is my trigger:

{Sam0102.securoad.local:snmptrap["Internal Temperature NTI"].nodata(1h)}<>1

But what this actually means is:

If there is no no data in the last hour from the "item Internal Temperature NTI" and if the data received is not equal to the constant 1 (because off <>1) the trigger will fire.

But what does the constant 1 exactly do in the nodata() function?