For large network, it means when this option exists.
JAG3D does not analyse the topology of your network. There is no loop, line, traverse etc. There are only observations between two points to be analysed. Moreover, most (digital) leveling instruments analyse the loop error during the fieldwork. Maybe, you can use such function.
Anyway JAG3D program is great.
applied-geodesy.org - OpenSource Least-Squares Adjustment Software for Geodetic Sciences