What do you mean by fixed term employment?

Employees are on a fixed-term contract if both of the following apply:

• they have an employment contract with the organisation
• they work for their contract ends on a particular date, or on completion of a specific task, eg a project

They may be a fixed-term employee if they are:

1. a seasonal or casual employee taken on for up to6 months during a peak period
2. a specialist employee for a project
3. covering for maternity leave.

I would like to know what is the legislation which concerns what you say about fixed-term contracts?