# Transmission of the calculation formula — NB view The calculation formula is transmitted for all market locations, irrespective of the number of metering locations relevant for calculating the energy at market location level. For every market location of the location bundle, the NB transmits the calculation formula for determining the values of the respective market location to every MSB that is assigned to a metering location of the location bundle. The NB transmits the associated calculation formula to the LF that is assigned to a market location, even if no metering location and therefore no MSB is assigned to that market location. In the event that the calculation formula cannot be transmitted as part of the electronic data exchange, the corresponding contact of the NB is to be stated at this point so that a bilateral transmission of the calculation formula can be carried out. The calculation formula represents the formula for calculating the values of the market location, stating the required metering locations and their measurands. It specifies how the determined values of the individual metering locations are to be offset in order to form the values of the market location. ## Process flow from the perspective of the NB \nSystem diagram: Übermittlung der Berechnungsformel — view of NB\n\n\nCustomer backend system\n\nMACO APP · NB\n\nMarket partner\n\n\n\nProcess trigger received\n\nSTART_BERECHNUNGSFORM\nEL\n\nAPI\n\n1. Berechnungsformel\n\n\nMSB (entspricht dem M…\n\nAS4\n25001\n\nUpdate transaction\n\n\nUpdate process data\n\nAPI\n\n2. Antwort auf\nBerechnungsformel\n\n\nMSB (entspricht dem M…\n\nAS4\n25010\n\nAPERAK check: Z33\n\n\nUpdate transaction\n\n\nUpdate process data\n\nAPI\n\nProcess trigger received\n\n\nSTART_BERECHNUNGSFORM\nEL\n\nAPI\n\n4. Berechnungsformel\n\n\nLF\n\nAS4\n25001\n\nUpdate transaction\n\n\nUpdate process data\n\nAPI\n"} gesamt={"\nSequence diagram: Übermittlung der Berechnungsformel — view of NB\n\n\nBackend (customer)\n\n\nMACO APP · NB\n\n\nMSB (entspricht dem MSB a…\n\n\nLF\n\n\nSTART_BERECHNUNGSFORMEL\nTrigger event\n\n1. Berechnungsformel\nAS4 · PI 25001\n\nUpdate transaction\nUpdate process data\n\n2. Antwort auf Berechnungsformel\nAS4 · PI 25010 · E_0218\nE_0218 — Berechnungsformel prüfen\n\nUpdate transaction\nUpdate process data\n\nSTART_BERECHNUNGSFORMEL\nTrigger event\n\n4. Berechnungsformel\nAS4 · PI 25001\n\nUpdate transaction\nUpdate process data\n"} titel="NB" /> ## Process steps ### Calculation formula
**Check identifiers** - [25001](/en/schnittstellen/202610/pruefi/UTILTS/PI_25001) — Calculation formula · AS4
**Flow**
  1. **Prozessauslöser** [`START_BERECHNUNGSFORMEL`](/en/api/202610/ausloeser-nb/start-berechnungsformel) \",\n \"verwendungAb\": \"\",\n \"zeitraumId\": null\n }\n ]\n },\n \"transaktionsdaten\": {\n \"absender\": {\n \"rollencodenummer\": \"\"\n },\n \"empfaenger\": {\n \"rollencodenummer\": \"\"\n },\n \"kategorie\": \"\",\n \"lokationsId\": \"\",\n \"lokationsTyp\": \"\",\n \"sparte\": \"\"\n },\n \"zusatzdaten\": {\n \"eventname\": \"START_BERECHNUNGSFORMEL\",\n \"prozessId\": \"\"\n }\n}"} security={[{"bearer": []}]}>Ausprobieren The backend triggers this step with this event.
  2. Message to **MSB (corresponds to the MSB at the metering location object)** · AS4
  3. **Write endpoint** - Transaction updated — [Update process data](/en/api/202610/backend-schreiben-nb/updateprocessdata#prozessdaten-aktualiseren) `POST /updateProcessData` Try it out Updates the existing transaction in the backend once the message has been created.
### Response to calculation formula
**Check identifiers** - [25010](/en/schnittstellen/202610/pruefi/UTILTS/PI_25010) — Response to calculation formula · AS4
**Flow**
  1. Message from **MSB (corresponds to the MSB at the metering location object)** · AS4
    **Response per decision tree** - `25010` → [E_0218](/en/referenz/202610/ebd/E_0218) · MSB · Check calculation formula
  2. **APERAK checks** - `25010` → `Z33`
  3. **Write endpoint** - Transaction updated — [Update process data](/en/api/202610/backend-schreiben-nb/updateprocessdata#prozessdaten-aktualiseren) `POST /updateProcessData` Try it out Updates the existing transaction in the backend with the data of the incoming message.
### Calculation formula
**Check identifiers** - [25001](/en/schnittstellen/202610/pruefi/UTILTS/PI_25001) — Calculation formula · AS4
**Flow**
  1. **Prozessauslöser** [`START_BERECHNUNGSFORMEL`](/en/api/202610/ausloeser-nb/start-berechnungsformel) \",\n \"verwendungAb\": \"\",\n \"zeitraumId\": null\n }\n ]\n },\n \"transaktionsdaten\": {\n \"absender\": {\n \"rollencodenummer\": \"\"\n },\n \"empfaenger\": {\n \"rollencodenummer\": \"\"\n },\n \"kategorie\": \"\",\n \"lokationsId\": \"\",\n \"lokationsTyp\": \"\",\n \"sparte\": \"\"\n },\n \"zusatzdaten\": {\n \"eventname\": \"START_BERECHNUNGSFORMEL\",\n \"prozessId\": \"\"\n }\n}"} security={[{"bearer": []}]}>Ausprobieren The backend triggers this step with this event.
  2. Message to **LF** · AS4
  3. **Write endpoint** - Transaction updated — [Update process data](/en/api/202610/backend-schreiben-nb/updateprocessdata#prozessdaten-aktualiseren) `POST /updateProcessData` Try it out Updates the existing transaction in the backend once the message has been created.
Decision trees of this process | EBD | Name | |---|---| | [E_0218](/referenz/202610/ebd/E_0218) | Check calculation formula |
## Process information Wording of the consolidated version, profile ch. 2.3.1, pp. 16–17.
  1. ### Preconditions Precondition for sending the calculation formulas to a MSB: - The MSB is assigned to a metering location of the location bundle.
  2. ### Results - The MSB of the metering locations are able to provide the required values to the MSB of the market location at the required point in time. - The MSB of the market location is able to determine the values of the market location. - The LF of the market location is able to check the values of the market location transmitted to it.
  3. ### Error case #### Result in the error case If the rejection of the calculation formula by the MSB is caused by asynchronous master data of the NB, the NB has the option of correcting this by means of the use case master data change (here SD “[Master data change initiated by the NB (responsible)](/en/prozessdoku/202610/NB/GPKE-Teil4-stammdatenaenderung-vom-nb-verantwortlich-ausgehend)”) (GPKE part 4) in order to then send the calculation formula to all authorised parties again. #### Error cases - Calculation formula is incorrect or incomplete - Missing calculation formula
  4. ### Trigger - Reassignment of MSB to a metering location of the location bundle or - when a calculation formula changes or - Extension of the location bundle by a market location. Precondition for sending the calculation formulas to LF: - The LF is assigned to the market location. Trigger: - Reassignment of LF to a market location or - when the calculation formula for the market location changes (whereby the calculation formula must be sent to the currently assigned LF as well as to all those assigned to the market location in the future).
  5. ### First message The party involved on this page is itself the sender of: „Calculation formula“ to **MSB (corresponds to the MSB on the metering location object)** (step 1).
  6. ### Objective Every MSB assigned to the location bundle has the calculation formula for each market location of the location bundle. The LF has the valid calculation formula for the market locations assigned to it.
## Other views of the process The same process through the eyes of the other parties involved: the same steps, each read from their point of view. - [View LF](/en/prozessdoku/202610/LF/WiM-Teil2-uebermittlung-der-berechnungsformel) — LF - [View MSB-MELO](/en/prozessdoku/202610/MSB/WiM-Teil2-uebermittlung-der-berechnungsformel) — MSB at the metering location object · market role MSB *The steps are the **possible** messages of this process, not a sequence — the source lists neither conditions nor alternatives. The small box on the step names the own view on the left: with **←** it receives, with **→** it sends. Collapsed steps run between other market partners. The numbers are those of the source; where one is missing, it is missing there.*