Pilot fish has coded a large Excel macro for one of his company's unit managers -- and it's been running without problems for years.
"The macro reads a raw data file, extracts and manipulates a bunch of the data in the file, and then creates a summary report and a detailed report of the data," says fish.
"But last week that manager let me know that the format of the data file is changing, so the data will be in different columns than they are now. He wanted to give me a heads-up, since the reports that are created won't be accurate, given this new raw file format."
You'll be fine, fish tells him. Just run the macro as you normally do.