These are the jobs Spanline actually runs. A longer note on the file format is on the .pl5 import page, and the arithmetic is on the link budget page.
Two sites yield the Vincenty path length and both azimuths on WGS84. The length is not rounded before that inverse. A new site starts with a minimum antenna height of 15 ft. A new hop starts with 150 ft centerlines unless a site minimum is higher.
Spanline imports a Pathloss 5 .pl5 and exports one. The imported profile stands in until elevations are fetched. Export stays off until the project has a site.
The Fetch elevations control reads USGS 3DEP bare earth from the National Map. Clutter tries 3DEP lidar height above ground, then LANDFIRE vegetation height, then an OpenStreetMap building that carries a height or a level count, then an Annual NLCD class height. Those heights can be edited. Clearance uses the higher of clutter and an obstruction entered by hand. It does not stack them.
If a profile has no interior terrain sample, clearance says “No terrain”. That is not a failure.
Multipath availability uses Vigants. Rain uses Crane and ITU-R P.838. The rain region comes from the path file when one was imported.
With a signed-in session, Find ASR searches the weekly FCC registration file near a coordinate, and Look up reads one registration number. The elevation lookup and the city lookup do not require an account. The app does not download the FCC file. That import is a separate step on the server.
Performance and the printed report share one link budget. When a radio has adaptive modes, Spanline shows the selected mode, not a second single-threshold summary. The report prints on letter paper in portrait.
With no account, projects stay in this browser and Spanline does not call the project API. With an account, plans are free, paid, and admin. Any signed-in plan stores projects on the server. Private catalog writes need a paid or admin plan. Shared catalog writes need an admin plan.
Free to use in the browser; sign-in saves projects.