Your running a 10.5 server with (SUS) software update services and you’ve got 10.6 clients on your network. You want to patch your 10.6 clients but they won’t with 10.5 SUS. The Apple solution is to upgrade the server to 10.6 so it can serve 10.6 updates. An alternative solution is to use the following hack on the 10.5 SUS. [...]

Yes, the dot underscore (DS_Store and ._ AppleDouble files) are gone. They have been replaced using SMB Alternative Data Streams (ADS) also known as NTFS Streams. As a network administrator, I welcome this but it may have repercussions. [...]

MacOS X Leopard (10.5) doesn’t save resource fork information (._ hidden files) on the Isilon by default. Leopard uses the Isilon SMB Alternate Data Streams (ADS) feature which allows metadata such as resource fork data to be stored. However, MacOS X Tiger (10.4) cannot use ADS. Therefore, files (without extensions) written to the Isilon from Leopard(10.5) cannot be identified by Tiger (10.4) unless ADS is disabled. [...]