[openrailwaymap] Tagging dual electrified tracks

One of the issues that we've faced in improving the electrification tagging in the UK is dual electrified tracks. At some locations in the UK - and I believe in most countries - different electrification systems meet and overlap, with an overhead contact system and a ground-level contact system co-existing on a single track for a short distance. We have around 10 of these locations in the UK, some with multiple tracks. There is currently no guidance given to taggers on how to treat these tracks AFAIK. Has anyone already looked at this? We were thinking to use the standard OSM key=<value1;value2> syntax to identify these tracks. As an example, a single track provided with both 25kV 50Hz AC overhead line and 750V DC third rail would be tagged as follows: electrified=contact_line;rail voltage=25000;750 frequency=50;0 Thoughts welcome!