Hello Agnes,
Production order types are not plant specific, they are maintained at client level hence you wont find any order type in T003O tables.
They get assigned to a particular plant when you extend these order type using transaction OPL8 (in case of production orders). This can be seen in customizing table T399X
Every order type is assigned to a key called Order category that specifies tothe area to which these orders belong. e.g. for production order its always 10, for internal order its 01 etc.
Can you please elaborate your exact requirement ?
Regards,
Rohit