Read the following case study:

XYZ company wishes to create a database to control its product. All products in the company only consist of three categories, such as clothing, food, and stationery. Each product is known by its product name and number. Clothing category consists of size and type; whereas food category consists of expire date and its weight. Stationery category has information such as type and brand. A single product must be classified in one category and cannot be classified in two or more categories: For an example, pen is in stationery category and cannot be classified in clothing or food category. There are many employees in XYZ company that can be identified by employee number and other details such as name, phone number and address. An employee raises a purchase order when a product or more need to be reordered from the supplier. The purchase order is identified by its unique number, date and details. Supplier will receive several purchase order from employee. There are several employees in charge in raising a purchase order. Supplier is identified by supplier unique number, name and contact number.

Identify all possible entities involved in the above case study. For each entity determine the relevant attributes and indicate the primary key attributes with PK abbreviation in bracket (i.e. (PK)). Based on the identified entities, draw a complete Entity Relationship Diagram (ERD) including the Enhanced Entity Relationship (EER) concepts if applicable, showing all the necessary relationships and multiplicity constraints.