* @return true if the field was signed, false if the field was not signed or not found
     * @since 5.0.5
     */
    public boolean clearSignatureField(String name) {
        sigNames = null;
        getSignatureNames();
        if (!sigNames.containsKey(name))
            return false;
        Item sig = fields.get(name);
        sig.markUsed(this, Item.WRITE_VALUE | Item.WRITE_WIDGET);
        int n = sig.size();
        for (int k = 0; k < n; ++k) {
            clearSigDic(sig.getMerged(k));
            clearSigDic(sig.getWidget(k));
            clearSigDic(sig.getValue(k));
        }
        return true;
    }