When internal auditors are preparing workpapers for the testing stage of an engagement, which of the following guidelines should be observed?

1. Include copies of all client files that were reviewed for the audit.

2. Avoid the use of professional, industry-appropriate jargon and technical terms.

3. Indicate the original sources of all data and information used in the workpapers.

4. Leave blank space for cross-references to be completed during the post-audit process.