Basecamp has replaced Mapsource as Garmin's default mapbrowser and has some nice features like 3D (not available on Openfietsmap, choose in Map Views 2D map - Ctrl+2), better track management, filtering road or waypoint types and better elevation profiles. However, routing is only compatible with the latest GPS devices (Etrex 10/20/30, Montana, GPSmap62, Oregon x50). For other devices, Mapsource is recommended.
In the menu Utilities-Options (Ctr+O) > Add Activity Profile:
Add Activity Name: OFM
Activity Type: Automotive or Driving (v.4.1)*
Road Type Avoidances:
Feature Type Avoidances:
*) In the activitiy types Bicycling/Tour cycling carpool lanes are automatically avoided, which means in OFM this avoids unpaved/gravel bikepaths. Also Toll road avoidance is not available in this profile.
Acctivity type Walking will ignore oneway streets which can be useful in cities. Hiking will do the same but here are Interstates/Major highways selected and greyed out (interstates/major highways are cycleways and -routes on OFM)