This function loads a KVP attribute that has previously been saved to disk with the save_attr function. The values of these parameters persist between game crashes. Note that there is only one set of attributes per mob vnum or item vnum - you cannot use this function to store permanent data for an individual mob or item unless it's unique.
Once the KVP attribute has been loaded, it can be accessed with get_attr in the usual way. Unlike many of the other xxx_attr functions, load_attr always puts the loaded value on the currently executing MUDL proc.