The Celestial Filing Depository is a big library in the sky where all information from the beginning of the time is stored. It consists of five branches, each with an infinite amount of filing space. The first branch deals with the important issues of time, space and celestial motion. The fifth branch (where Rumisiel was, until recently, employed) deals with fairly mundane aspects of life on earth.
Originally there was only one big filing depot believed to have been created by God. Every angel just hung around doing their tasks, but it was very disorganized until Lucifer created a framework and a power structure, like a big corporation, with Lucifer himself as the chief executive officer. Everyone fell into line and were happy. But pretty soon, the greedy Lucifer orchestrated a hostile takeover to own all the power in the universe, as he wasn't satisfied by just being in charge of it. As God is all knowing, he knew what was going down, and there was a big war, and God fired Lucifer. Lucifer didn't take kindly to being fired, so he went to Hell, and took most of his board of directors and senior management from the filing depot with him, setting up sort of a rival company. To keep anyone else from ever attempting to control the universe again, the depot was split in to five smaller companies, each with their own staff.
Files consists of lists of numbers comprehensible only to an elite few. While the files themselves are self-maintaining, union regulations require random selections to occasionally be checked for errors, so files are occasionally pulled and re-filed for no other reason than to be glanced at. In addition, occasional adjustments are made to correct for karma and other unforseen events. Still, the numbers in the files themselves are meaningless without the filing cabinets. The cabinets are like huge analog computers that translate the otherwise incomprehensible numbers into reality. For instance, the number that determines the length of a giraffe's neck in the "giraffe" file, might also determine the thickness of a whale's blubber if placed in the "whale" file. Files correctly entered into the system are all updated as the universe changes. Improperly filed files generate errors and are processed, but not updated properly, resulting in a disconnection with the universal defined reality, otherwise known as a "UDR Error". This is why Ash Upton and Emily McArthur retain the memories of their previous lives; the contents of their files no longer match the descriptions of their files as entered on the "table of contents" on the inside cover of each individual file. While the bodies have been updated, the souls cannot be located for updates, and the memories are retained. Since the files themselves now recognize Ash Upton as a girl and Emily McArthur as being two years younger, all correctly filed files have been updated to reflect this altered reality. If the files were replaced correctly, the universe would return to normal. Conversely, if the tables of contents of Ash and Emily's files were altered to reflect the current reality, the files would recognize them as being correct, and Ash and Emily would be "updated" and no longer remember their previous lives.
Having recently pulled both files, it was a relatively simple task for Rumisiel to remember the names of each person pulled from that day, and since they were all from the same region that was being checked by central, make his way to the relatively small town of Tempest and look up the only two people on that list of names that were totally freaking out.
Since the misfile, Rumisiel has lived in Ash's house, pretending nothing bad has happened, so Rumisiel can fix his mistake when he is able to return. If Rumisiel's bosses Terrael and Fillaniel discover the misfile, they will try to cover the mistake and correct the files by making Ash believe he was always a girl, and Emily's lost years will vanish permanently.