(efi_area)=

# Aggregation of areas

An optional modelling feature was introduced in version 9, enabling aggregation of areas when computing the PTDFs. We refer to the aggregate areas as prices areas. Thus, the simulated power prices will be the same for all modelled areas within a price area.

This file contains the following data:
- Header counter (Number of aggregated price areas for computing PTDFs)
- Aggregation parameters

## Example complete file

```
5,                                                           # Number of aggregated price areas for computing PTDFs
4,1,2,3,4,'NO4',                                             # No of areas for price area aggregation, areas to aggregate, price area name
3,5,6,7,'NO3',                                               # No of areas for price area aggregation, areas to aggregate, price area name
3,8,9,13,'NO5',                                              # No of areas for price area aggregation, areas to aggregate, price area name
3,10,11,12,'NO2',                                            # No of areas for price area aggregation, areas to aggregate, price area name
2,14,15,'NO1',                                               # No of areas for price area aggregation, areas to aggregate, price area name

```

## Header counter

Total number of aggregated price areas for computing PTDFs

Record format:

```text
<The number of aggregated price areas for computing PTDFs>,
```

Example:

```text
3,
```

## Aggregation parameters

Record format:

```text
<Areas for price area aggregation>, <areas to aggregate,...>, <price area name>
```
Example:

Aggregate 4 areas for the computation of PTDFs. The areas to aggregate are area 1, 2, 3 and 4 and the aggregated area name is NO4.

```text
4,1,2,3,4,'NO4',  # No of areas for price area aggregation, areas to aggregate, price area name
```