What does it mean?
A variation order records an instructed change to the contracted works through the procedure applicable to the project. It may change quantities, quality, sequence or scope. The instruction, entitlement, valuation and programme consequences are separate questions. A changed quantity is useful evidence for pricing, but it does not on its own establish contractual entitlement or an agreed valuation.
In practice
Increasing a slab from 150 mm to 200 mm over 24 m² adds 1.2 m³ of concrete. Reinforcement, formwork edges, labour and time effects should be assessed separately where applicable.
Keep in mind
For a project record, note the document reference, revision and agreed measurement or contractual basis beside the quantity. Keep assumed information visibly separate from confirmed information. If two parties use different definitions or inclusions, resolve that difference before comparing amounts. These explanations are general estimating context; the wording of the applicable contract and its administration process must be checked for the particular job.