rsdb/reco_add_error_codes is a SAP Parameter attribute which is used to control add or remove DB error codes that lead to DB reconnect information. This is available within R/3 SAP systems depending on the version and release level.
Below is the standard documentation available and a few details of the attributes values .
With this parameter you can defined DB return codes that lead to a DB
reconnect For example:
rsdb/reco_add_error_codes = +1037, +2405 -8902, +1234 The setting above has the result that the error codes 1037, 2405, and 1234 of the class of the reconnect are added and the error code 8902 is removed from this class. The error codes can be specified in any order with any separators (or none) for the parameter above. It is only important that there is either a '+' or '-' before the error code. A maximum of 10 error codes with '+' and '-' are evaluated. If more error codes are specified, then these are not considered.
See SAP Parameter Documentation for full SAP documentation for this profile parameter.