Rendu almost same. Renditlonu pit lines ki teesukelli full maintenance chestaru.
PM ante rake arrange chesina zone CDO lo cheedhi. SM ante destination lo chesedhi.
For example, 12721/22 rake owner HYB CDO di, so it is the 'primary' depot. So, HYB lo jarigaedhi primary maintenance. Delhi just destination anthe, so NZM lo maintenance chesthe danni 'secondary' maintenance antaru.
SM is not...
more... always necessary. Distance traveled batti SM chestaru.
If maintenance at pitlines is not required, then they will either do Platform attention (Just clean on the platform and start return journey, like most intercities) or they can take it to the depot for some basic maintenance (washing etc), which is called 'Round trip attention at Depot'.