The efficiency and precision of the technique have been demonstrated by generating and comparing RNA models to their consensus structures determined by X-ray crystallography. Tests with RNA hairpin loops have produced structures of less than 2A of rms deviation from the crystal structures [19][9]. The system was later improved for the modeling of larger RNAs and the reproduction of transfer RNA (tRNA) models within the range of 3 to 4A of rms deviation have been obtained [18]. The program has also been used for the construction of a model of the Rev-binding element of HIV-1 using data derived from the analysis of aptamers [16].