Usually a ring-bound folder or electronic database which stores the candidate's evidence.

Some standards for evidence portfolios are:

• Clearly labelled with candidate's details
• All evidence should be verified (as a true copy; is the candidate's work, etc) 
• should be indexed and cross-referenced to the performance criteria for easier location

May also include:

• training records
• employment history (job titles, duties)
• workplace experience (projects and types of equipment)
• rail episodes