Merging networks is achieved with a Network program. This is controlled within the LINKMERGE and NODEMERGE phases:

• NODEMERGE: iterate over node list, merge records, compute node-based variables
• LINKMERGE: iterate over link list, merge records, compute link-based variables

MERGE control statement specifies how to merge records from different files, and how to combine variables in a merged record:

• If RECORD = F => Only records in the FILEI with lowest index [#] are included
• If RECORD = T => Any unique record from the different FILEI is included, whilst not-unique records are combined. The following subkeywords can be used to specify how to combine attributes values across multiple link or node records: FIRST, LAST, AVE, SUM, MAX, MIN, CNT, AVEX0

Example below:

Network 1 contains the record below (one of the records as example):

Network 2 contains the records below (two of the records, as example) - note the different additional attribute "REF_CODE":

With the following script file:

The output network will contain the merged and combine records, with the values below for those records in the example:

To only obtain the REF_CODE from Network 2, without merging and combining the other attributes, it would have been sufficient to use MERGE RECORD = F (False, i.e., read in the input net twice, but don't merge the records), and within the LINKMERGE Phase the script below:

REF_CODE = li.2.REF_CODE