Some units may only be taken if you have taken specified other units first, or if you take specified units at the same time or in the same year. These restrictions are known as unit rules.
It is important that you check whether or not they apply to you, as they may affect your choice of other units. This information can be found in the 'Requisites' section of the catalogue page for each unit.
There are four types of rule to cover this sort of relationship between units:
|Rule Type||Definition||Shown in the catalogue with the following text...|
|Pre-requisite||Units you must have taken in a previous year or semester in order to study this unit.||"Before taking this unit you must take..."|
|Co-requisite||Units you must take within the same year or semester in order to study this unit||"While taking this unit you must take..."|
|Excluded units||Units you cannot take if you study this unit.||"In taking this unit you cannot take..."|
|Post-requisite||Units you must take after taking a particular unit.||"After taking this unit you must take..."|
Units may also have other restrictions on their availability (for example, "You must have A-level XXX or equivalent in order to take this unit", "This unit is only available to students on XXX programme" etc.) This information will be displayed in the Requisites section of a unit description alongside any rules in the categories listed above.