In classic MacOS they were stored directly in attributes in the filesystem (HFS) and were handled by their proprietary network file sharing (AFP). On foreign fi

In classic MacOS they were stored directly in attributes in the filesystem (HFS) and were handled by their proprietary network file sharing (AFP). On foreign file systems (mainly FAT32, UDF was also supported), icon placements were simply not remembered. Since NeXTSTEP (and hence early OS X) had boot drive support for other file systems (UFS) and other networking standards (NFS) they needed a generic solution that worked everywhere. https://en.wikipedia.org/wiki/Hierarchical_File_System#Design https://en.wikipedia.org/wiki/Hierarchical_File_System#Desig... > The File Record also stores two 16 byte fields that are used by the Finder to store attributes about the file including things like its creator code, type code, the window the file should appear in and its location within the window > Like the File Record, the Directory Record also stores two 16 byte fields for use by the Finder. These store things like the width & height and x & y co-ordinates for the window used to display the contents of the directory, the display mode (icon view, list view, etc.) of the window and the position of the window's scroll bar.