  The coherent electron transport along zigzag and metallic armchair graphene
nanoribbons in the presence of one or two vacancies is investigated. Having in
mind atomic scale tunability of the conductance fingerprints, the primary focus
is on the effect of the distance to the edges and inter vacancies spacing. An
involved interplay of vacancies sublattice location and nanoribbon edge
termination, together with the spacing parameters lead to a wide conductance
resonance line shape modification. Turning on a magnetic field introduces a new
length scale that unveils counter-intuitive aspects of the interplay between
purely geometric aspects of the system and the underlying atomic scale nature
of graphene.
