To specify document type for depreciation posting you need to first create it in sap. You can either create on your own or copy and modify it accordingly for your use. SAP has delivered a standard document type AF for depreciation posting. If you want to use that then you can do so.
Whatever document type you have defined in sap it must be assigned and specified for Dep posting.
You can create it or can check the standard SAP document type by using transaction code OBA7. You can also use below path;
SPRO > Financial Accounting > Financial Accounting Global Accounting > Document > Document Header >Define Document Types
Specify for Dep Posting
After creating it you need to specify it for depreciation posting. To do that use transaction code AO71 or below path;
SPRO > Financial Accounting > Asset Accounting > Integration with General Ledger > Post depreciation to the general ledger > Specify document type for posting of depreciation
Here you just mention the document type AF against your company code.
Relevant field in Dep posting
If you want a different number range to be set for depreciation posting then that can be done by assigning the created number range to it by using transaction code OBA7.
In case you want to reverse your depreciation posting in sap then the reverse document type will be used. It is used because in SAP report it will be easy to differentiate different transactions easily.
In a depreciation posting document type, only two accounts are allowed as those accounts are only accounts which are used for these transactions. Those are;
- G/L Accounts
Under the control data option we need to allow negative posting and inter company posting.