In outside plant it is critical to know the exact location of all underground (subterranean) networks. This is especially true for fibre optic networks where there is no metallic element in the cable. Marking the network will save time and effort and costly mistakes on maintenance, re-entry and new installations. 3M Telecommunications offers an advanced technology product portfolio for electronically marking the underground network. With 3M EMS and Locators it is possible to map the FTTX network and trace it precisely.