You can't take a hard copy financial report (or a PDF file or a Microsoft® Excel file for that matter) and automatically feed it into your data analysis system. If you want to convey the information in context into another report or another system, it has been necessary to either re-key it or produce a customized interface from one system to another. By conveying context at the same time as content, XBRL removes the requirement to re-key or develop customized information feeds.
Consider the spreadsheet below. It takes you only a moment to work out that the item surrounded by the blue square is 16,000 in Tangible Assets for the 2002/2003 financial year. You worked that out by synthesizing all of the context that surrounds that blue square. We have highlighted some of the most important with arrows. Now think about the way a computer might digest the contents of the blue square. At best, the computer will know that the number 16,000 appears at cell reference C8. At worst, it will just know '16,000'. XBRL allows systems to communicate the entire context that a human needs to fully understand a concept.