  Let $(P_d)$ be any prime of $\mathbb{F}_q[t]$ of degree $d$ and consider the
space of Drinfeld cusp forms of level $P_d$, i.e. for the modular group
$\Gamma_0(P_d)$. We provide a definition for oldforms and newforms of level
$P_d$. Moreover, when the dimension of the vector space of oldforms is one and
$P_1=t$ we prove that the space of cuspforms of level $t$ is the direct sum of
oldforms and newforms and that the Hecke operator $\mathbf{T}_t$ acting on
Drinfeld cusp forms of level 1 is injective, thus providing more evidence for
the conjectures presented and stated in [2] and [3].
