Table 3.

Variables of interface data.

Variable	Description
erasmus_id	The standardized form of the Erasmus HEIs.
GRID_id	The GRID ID related to each Erasmus HEI. If this field is blank, no connected research institution exists in the GRID database.
countif_GRID	The number of Erasmus HEIs connected to the GRID institutions. More than one means that the GRID institution is connected to more than one Erasmus HEI probably as a result of a merger.
ETER_official	This variable was extracted from the ETER database which contains the Erasmus code and indicates the improvement of original open data (new connections, corrections).
ETER_geo	To ensure the transparency of this work, connections based on adjacent locations are published.
ETER_SPSS	To ensure the transparency of this work, connections based on textual similarities are published.
ETER_master	The ETER ID related to each Erasmus HEI. If this field is blank, no universities are connected in the ETER database. This variable validated based on the ETER_official, ETER_geo, ETER_SPSS variables.
ETER_master2	Additional ETER ID used when the ETER_master has been changed due to the transformation of the HEI
countif_ETER	The number of Erasmus HEIs connected to the ETER universities. More than one means that the ETER institution is connected to more than one Erasmus HEI probably as a result of a merger.
ETER_notes	Some difficulties were noted concerning transformations of the HEIs or mistakes in the official database.