
Each document type is identified by a two-digit abbreviation and a description. It classifies the document (receivable, payment).
Each document type can be used for manual postings (cash desk) or mass processing (payment run).
Each document type is allocated to a number range to determine the document number intervals. The number range also determines whether document numbers are assigned internally or externally.
Document number ranges are specified depending on the volume of the processes.

In addition to the document number ranges for manual postings, additional number ranges must be defined for business transactions that result from parallel mass processing (invoicing, payment run).
The key for the mass processing number range must begin with a letter. Since parallel mass background processes obtain their document numbers from these number range intervals, they must be defined based on the expected data volume and the number of parallel background processes.
If individual postings of a certain category are frequently executed online (cash desk) and if all postings are executed with the same document type, users may have to wait because all users access the same number range when document numbers are assigned. To reduce or avoid this waiting period, you can allocate multiple number ranges for individual postings to a document type.

The document header contains general data such as document number, document type, document date, posting date, currency, and reconciliation key.
Data about the person making entries and the origin is stored in the document header as well.
Data relevant for posting is stored in the business partner items. This includes the business partner and/or the contract account number, the FI-GL receivables account (balance sheet), the receivables amount, the due date, the clearing information, and much more data.
Data relevant for the offsetting posting is stored in the general ledger items. This includes the FI-GL revenue account (profit and loss statement), the tax account (balance sheet) and the tax key.
Offsetting items and tax lines are created automatically, so only the data of the business partner items must be entered by the user.
You can use transaction FS00 to display the master data records of the FI-GL accounts (receivables, revenue, tax).

The repetition document is used in installment plans, where the receivable typically consists of many of the same line items that differ only in their due dates.
The repetition item is a fictitious line item in a repetition document, composed of the data of the sample record of an item and the repetition details.
The repetition item of the installment plan is posted statistically, as it refers to a source receivable which is originally posted as a real item.

The clearing document, which can be posted for example during incoming payment, consists only of a document header and the offsetting item.
The following information is stored in the offsetting item:
- The payment amount
- The FI-GL bank account
- Information on the cleared document
The document number of the clearing document, the clearing date, and the clearing amount are stored in the business partner item of the cleared document.
This means that both documents are linked as long as the clearing exists. The payment does not maintain a business partner item because all information on the business partner item can be viewed in the linked receivables document.
If clearing is reversed, the connection between the clearing document and the receivable is deleted and the payment document receives a new business partner item with all posting information.
The clearing information is stored in the clearing history of the payment document even if clearing is reversed.

If the payment results only in partial clearing, the item in the source document is split into an open subitem and a cleared subitem, where the clearing information (payment amount and document number) is stored.

A diagram explains the differences between posting real and statistical items in FI-CA.
Post as real Item is when A real item is transferred to the general ledger. A real item is included in all processes relevant for general ledger. Post as statistical Item is when a statistical item is not transferred to the general ledger. A statistical item is relevant for dunning and interest calculation. A statistical item can be paid or cleared. In this case, it would then be transferred to the general ledger.

Statistical postings make it easier to deal with uncertain receivables, since these postings are not transferred to the general ledger and, as a result, are easier to reverse if they are not paid. Typical examples include dunning charges or installment plan items because the underlying source receivables have already been posted in the general ledger.

Statistical documents are comprised of only a document header and business partner items.
Statistical documents are not forwarded to the general ledger.

When statistical items are cleared, for example by a payment, the clearing information is stored in the statistical document. A real business partner item (relevant for the general ledger) is created simultaneously in the payment document and cleared immediately.
You can use posting area 1010 to determine the main and sub transaction of the automatically generated real item.
Revenue and tax lines are added to the offsetting item.