Full Idea
Events and objects that have ceased to exist change their A-series position (by becoming increasingly past), but persisting objects, in contrast, change their present B-series position.
Gist of Idea
Things which have ceased change their A-series position; things that persist change their B-series position
Source
Robin Le Poidevin (Intro to 'Questions of Time and Tense' [1998], 1 n2)
Book Reference
'Questions of Time and Tense', ed/tr. Le Poidevin,R [OUP 2002], p.3
A Reaction
The second half seems to imply a 'moving spotlight' of the present. This distinction is important, as it creates problems for all theories. The asymmetry seems weird.