Roxor released Revision 21 (also referred to as r21). The patch adds a feature that allows players to bring custom songs from home and play them on the machine. Songs were created using StepMania, and the song files and accompanying audio files are stored on the player's USB card. When the player inserts their USB card into the machine they can then select the song from the game menu. The feature had some intentional limitations: The music file can be no more than 120 seconds (2 minutes) long. The music file must be in Ogg Vorbis format. Ogg music files must be less than 5 MB in size. Banners and song samples aren't loaded, and are thus absent from the song selection screen. Background images (whether still or video) aren't loaded; instead, random background videos run during play. However, background scripts that use In the Groove's background videos do work within r21. A maximum of 50 songs are loaded from each player's USB card. Time limits in the game's loading screens sometimes caused fewer songs to be loaded. An unofficial patch was later discovered online to circumvent the song length limit. Players could manipulate the metadata in the header of the OGG file to make the game think the song is only 1:45 long. The program which performs this patch is commonly referred to as the Ogg Length Patch program. This allows songs of any length to be played on the machine as long as the music file is still under 5 MB in size. Playing songs that are longer than 3 minutes is looked down upon by some arcade operators due to the possibility of losing money, and in some cases bans have even been issued on players who excessively play long songs when others are waiting in line to play. The Ogg Length Patch vulnerability as well as other bugs and timing issues were fixed in R23. While R23 has timing corrections and bug fixes, it forces all custom songs to end at 120 seconds of play regardless of the use of the Ogg Length Patch. Despite the timing fixes, Revision 23 is unpopular with the majority of ITG players. Even though some professional players prefer r23 due to the timing fixes, the strict time limit of 120 seconds was looked down upon since some official Dance Dance Revolution songs and even some official songs on the In