A column called “status” may be obvious to the person who created it and puzzling to everyone else. Instead of guessing from a few rows, write a small dictionary entry for that one column. The exercise often reveals what you need to ask the data owner.
Describe the field in a complete sentence
State what the value refers to and when it is recorded. “Status of the sample after the initial inspection” is more informative than repeating the heading. If the column contains numbers, add the unit and explain whether they are measurements or codes.
List the allowed values when the set is known. Include the meaning of blanks and special markers. Do not assume that an empty cell means the same thing as zero, not applicable, or not yet reviewed.
Test the definition against awkward rows
Choose a normal entry and one that looks unusual. Can the definition explain both? If not, mark the uncertainty and seek clarification rather than inventing an exception.
Record the source and date of the explanation. A dictionary should help a future reader interpret the field under the same rules you used. Starting with one ambiguous column is often more productive than creating a large document full of headings that merely restate themselves.