  In this note we consider boundary point principles for partial differential
inequalities of elliptic type. Firstly, we highlight the difference between
conditions required to establish classical strong maximum principles and
classical boundary point lemmas for second order linear elliptic partial
differential inequalities. We highlight this difference by introducing a
singular set in the domain where the coefficients of the partial differential
inequality need not be defined, and in a neighborhood of which, can blow-up.
Secondly, as a consequence, we establish a comparison-type boundary point lemma
for classical elliptic solutions to quasi-linear partial differential
inequalities. Thirdly, we consider tangency principles, for $C^1$ elliptic weak
solutions to quasi-linear divergence structure partial differential
inequalities. We highlight the necessity of certain hypotheses in the
aforementioned results via simple examples.
