A small correction (or at least an elaboration): The partition name, which you correctly say can be changed via the 'c' option in GPT fdisk, is unimportant with respect to whether OS X mounts the partition. That field in the GPT data structure exists to be informative to users. GPT fdisk, GNU Parted, and some other tools (but not Disk Utility) display this field. It can be handy in differentiating different partitions with the same type code but different purposes. For instance, Linux and Windows use the same type code for their native partitions, which can make it hard to tell what's what in a Linux/Windows dual-boot environment. Using the partition name field, you can give each partition a descriptive name, such as "Linux /boot" or "Shared NTFS data." Naming the EFI System partition in this way can be useful, but isn't necessary to keep it from mounting in OS X.