An MD5 file is not an accessibility content file. It’s an optional companion file mainly used for checking file integrity. MD5s are created by taking a digital file (any kind of digital file like a caption file or Word doc or video or audio; it truly works for any file) and running it through a program that generates a character string based on the particular data setup within the file itself.

The MD5 file itself is a plain text file. You can open and check it in a text editor. TechOps generates the MD5 string and sends it and the accompanying original file to the client. Then the client can generate an MD5 string on their end using the file they downloaded from us and compare the values.

If the values match up, it means that no data has been altered in the file from the point at which we sent it to when the client received it, so they have received the true original file.

If some data was corrupted during upload or download it would generate an MD5 which would return a string that wouldn't match the one above. That would be an indication that the file they have on their end is incomplete or corrupted or somehow not exactly what we originally sent them. It wouldn’t tell anyone how the file got changed or exactly what was wrong with it, but it indicates that the files are somehow different. So it is helpful for determining file integrity, but it does also have limited use in that respect and we don't generally recommend them to clients, we just accommodate already existing requests.