A question on capital and lower-case symbols

Dear Richard,
Dear Valerij,

Many sincere thanks for your messages. I am sure the
best for me is to follow Richard's suggestion and never use
upper case (and this I will try to do), but sometimes I
believe that the use of upper case is convenient (as is the case
reported by Valerij in itensor), e.g. (as far as I am concerned)
in composite words such as ShearForce and BendingMoment
in beam problems in structural mechanics. To be sincere, I
prefer to use the symbol ShearForce than shear_force. 

Moreover, in beam problems, q denotes the distributed loading
of the beam, but Q is a symbol of the shear force, i.e. sometimes
we use capital symbols for a quantity and the use of lower-case
symbols may lead to a confusion as far as the standard notation
is concerned.

My present question began from a wrong response (as far
as I can remember) from Maxima when in beam problems 
I differentiated Q (the shear force) to obtain q (the loading
distribution) and I failed. (I am not sure I can reproduce this
behaviour.) Now I am using p instead of q for the loading 
and Q for the shear force. I still do not like to use a lower-case
letter for the shear force.

In case that this "bug" reported in Richard's message could 
be fixed in some way in the future, this would be very nice.

Many sincere thanks again and best regards from Patras,

Nikos