例一:

A I 0.0
O M 9.0
AN I 0.1
AN M 12.2
= M 9.0

例二:

A M 640.0
AN M 640.1
O
AN M 640.2
A M 640.3
O M 640.4
= M 640.5
例三:

L MW 646
A OV
A OS
= M 641.0
O M 641.2
A M 641.3
= M 641.4
这三例中或语句如何理解,特别是例三中的O M641.2语句与前后语句的关系?