Functional template is used when the applicant has considerable gaps in his work history. These gaps make a bad impression on employer and hence should be hidden. This format is more focused on the skills rather than the experiences of the applicant.
First, you should identify what your template needs. At a minimum, your invoice should include certain elements, such as your companys name and address, customers contact information, description of services provided, and the agreed cost for the services you provide. More advanced invoices may include your companys logo, terms of payment, and itemization of goods and services provided.