  We study the homology and the Borel-Moore homology with coefficients in
$\mathbb{Q}$ of a quotient (called arithmetic quotient) of the Bruhat-Tits
building of $\mathrm{PGL}$ of a nonarchimedean local field of positive
characteristic by an arithmetic subgroup (a special case of the general
definition in Harder's article (Invent.\ Math.\ 42, 135-175 (1977)).
  We define an analogue of modular symbols in this context and show that the
image of the canonical map from homology to Borel-Moore homology is contained
in the sub $\mathbb{Q}$-vector space generated by the modular symbols.
  By definition, the limit of the Borel-Moore homology as the arithmetic group
becomes small is isomorphic to the space of $\mathbb{Q}$-valued automorphic
forms that satisfy certain conditions at a distinguished (fixed) place (namely
that it is fixed by the Iwahori subgroup and the center at the place). We show
that the limit of the homology with $\mathbb{C}$-coefficients is identified
with the subspace consisting of cusp forms. We also describe an irreducible
subquotient of the limit of Borel-Moore homology as an induced representation
in a precise manner and give a multiplicity one type result.
