SD/MS(?) card access in PRS 505 is buggy, but it should always work with "*via mount" (albeit quite a bit slower (might improve in the future, currently mount/umount is done every time) and with disabled scanning)
By the way, besides .noscan (which is honored even if scanning is disabled via settings menu) there is also "disable scan" option in PRS+ menu.
The rule is: English.non-English.English
Wow. Does it also work with underscore "_" as "english" letter?