public ushort Version

An allocator function is uniquely identified by its "combination" of AllocatorManager.AllocatorHandle.Index and AllocatorManager.AllocatorHandle.Version together: each index has a version number that starts at 0; the version number is incremented each time the allocator is invalidated. Only the lower 15 bits of Version is in use because when allocator version is larger than 0x7FFF, allocator.ToAllocator returns a negative value which causes problem when comparing to Allocator.None.