Assume that you are trying to build an operation interface which allows the mechanical engineering students in UNT to register for $9$ of the MEEN $3000$ level classes $($which are highlighted in blue as shown in $2019-2020$ MEE curriculum flowchart$).$

In order to register for a MEEN class, students need to meet all the prerequisites as well as co$-$requisites. Once he$/$she fulfilled all the conditions for a certain class, that class can be registered successfully. Otherwise the system will object his request and give that student a reminder why he$/$she could not register for that class.