userdata in Stateflow blocks

I am creating a signal managment system for certain parameters in a stateflow block. The user inputs information in a GUI and it is stored as a structure in the userdata of the stateflow block. However after applying the info to the userdata I get a warning saying that there is no function 'ceil' for type structure. Looking into this I realized that every new chart has a seemingly random number in the userdata upon adding it to the model and removing it causes errors. What is this number for and is it possible for me to use the userdata filed like I want too?

[Guy Rouleau]

Please technical support. In my opinion, the userdata property should be available to the user.