Context based assignment - context filter to display roles

Hi!!

I would like to make a guided task with a context named SYSTEM that contains values such as SAP ECC / SAP BW... and once the user selects the system (s) he wants (step 1), the appropriate roles (corresponding to the value of the context SYSTEM) display in step 2.

I assign the MX_CTX_TYPE to the roles. Roles having context type SYSTEM were well display. Then I add the MX_CTX_CONDITIONAL (by modifying the attr to allow assignment to MX_ROLE entrytype) to the same roles. But it seems that the filter is made at contexte type level and not value context level.

1 : Do you think if it's possible to use context value as filter for displaying roles in step 2?

2 : Do you know a way to filter on system for displaying roles in order to assign them to a user even if it's not a guided task? I tried to use the FIELD functionnality but it seems that it's not allow with the attribute type of MX_ASSIGNMENT.

Thanks,

Guillaume