I think you don't have to worry if you are not using APO.
As per my knowledge it basically used during creation of data in APO,
When you generate integration model, CFM1 transaction would allow you to select the relevant location types only. Meaning that when you select plant, you are able to select only the plants, and not customer or vendor, for example.
To specify in R/3 that a particular plant is a DC, you need to matain customization in SPRO at below location:
Production-> Distribution Resource Planning (DRP)->Basic Settings-> Maintain assignment of node type - plant
Give node type as DC in the above SPRO setting for the DC. For the plant, you don't maintain this setting.
During CIF, CIF interface would recongnize this SPRO setting and create a DC in APO after CIF.
Plant will be created as plant.
But why you want to make changes in node type?