A technical opinion is an evaluation of the technical condition of an installation and its facilities, issued based on an on-site inspection, available design documentation, and inventory records.

A technical expert assessment is also a technical opinion regarding the condition of an installation and its facilities, but it is extended with detailed technical and laboratory tests. Technical expert assessments are conducted when changes to the technical parameters of an installation are required (e.g., increasing or decreasing capacity, expansion), when the function or purpose of the installation is modified, or to evaluate the technical condition of a building or facility.