Siemens S7 STL Basics

Could someone refresh my memory how bit instructions works in STL in Siemens.

A     M      0.0
L     S5T#2S
SD    T      0

=     Q      0.0

Status of Q0.0 depends on RLO of A M0.0. If I modify a program little bit:

A     M      0.0
L     S5T#2S
SD    T      0

A     M      0.1
=     Q      0.0

Now status depends only on RLO of A M0.1, not on A M0.0 anymore. How's that?
Siemens manual says: You can terminate a Boolean bit logic string by using =/S/R, which is not this case.