Nuts-N-Bolts-N-Torque Socket grades

[Tony Rhodes <ARhodes@compuserve.com>]

I know that nuts and bolts come in various grades.

How do you differentiate them by sight?  I have seen some
bolts with lines on the top.  Usually I have seen 3 lines or 6 lines.
These lines are aligned radially pointing to corners.  Many
bolts I see have no markings.  I have never noticed any
particular markings on nuts.  How do you tell grades there?

In a similar vein, gow do you differentiate grades of
torque wrench sockets.  I have seen some with
no circumferential lines, others with one or two.  Do
these have any meaning?

-Tony
ARhodes@compuserve.com