Field RAM question

I'm not sure if I understand your question but $0867 is a RAM address, while $1850 is a SRAM address (SRAM is part of RAM). SRAM data is your save game data, meaning the "live" data is $0867 that is stored in $1850 prior or upon game saving. When you load a game, $1850 will be used to apply row or / and it will be transferred into $0867 that will do its job.

Edit: SRAM block is $1600 to $1FFF.