The formalised pattern assumed by a tRNA molecule viewed in two dimensions that shows the regions of internal complementarity that allow the polynucleotide to fold back upon itself into base-paired double helices. The stem includes the acceptor stem at the 3'-end, which attaches the amino acid, and the non-complementary loops or arms include the anticodon arm, which hybridises with the codon of an mRNA. In three dimensions the structure can be divided into two sections at a right angle to one another: a coaxial stack that includes the acceptor stem, and the remainder of the molecule, i.e. the common arm that is shared by the two sections.