where do mount take it filesystem type if none is writren

[Jabka Atu <mashrom.head@gmail.com>]

Hello..
I found some strange behavior (for what i know)
in my mount /dev/hda has ntfs-3g parttion type .
but when i do mount /dev/hda /mnt/location //without using -t ntfs-3g
it mounts it as _NTFS_ and not as _NTFS-3G_.
the question is why ?