Because official records of "shinengō" are lacking, the range of dates to which they apply is often unclear. For example, the well-known itsunengō is normally said to refer to 650–654 CE; a poetic synonym for the Hakuchi era. However, alternate interpretations exist. For example, in the Nichūreki, Hakuhō refers to 661–683 CE, and in some medieval temple documents, Hakuhō refers to 672–685 CE. Thus, shinengō may be used as an alternative way of dating periods for which there is no official era name.