<Li> In 2006, in the 8th edition of the formal definition of SI, the CIPM cataloged the dalton alongside the unified atomic mass unit as a "Non-SI unit whose values in SI units must be obtained experimentally: Units accepted for use with the SI". The definition also noted that "The dalton is often combined with SI prefixes ..." </Li> <Li> In 2009, when the International Organization for Standardization published updated versions of ISO 80000, it gave mixed messages as to whether or not the unified atomic mass unit had been deprecated: ISO 80000 - 1: 2009 (General), identified the dalton as having "earlier (been) called the unified atomic mass unit u", but ISO 80000 - 10: 2009 (atomic and nuclear physics) catalogued both as being alternatives for each other . </Li> <Li> The 2010 version of the Oxford University Press style guide for authors in life sciences gave the following guidance: "Use the Système international d'unités (SI) wherever possible...The dalton (Da) or more conveniently the kDa is a permitted non-SI unit for molecular mass or mass of a particular band in a separating gel ." At the same time, the author guidelines for the journal "Rapid Communications in Mass Spectrometry" stated "The dalton (Da) is a unit of mass normally used for the molecular weight...use of the Da in place of the u has become commonplace in the mass spectrometry literature...The "atomic mass unit", abbreviated "amu", is an archaic unit ". </Li> <Li> In 2012, in response to the proposed redefinition of the kilogram, it was proposed that the dalton be redefined as being 0.001 / N kg, thereby breaking the link with C . This would result in the dalton and the atomic mass unit having slightly different definitions, but the suggestion is that the older unit should be superseded by the "new" dalton . </Li>

What is the mass of an oxygen atom in atomic mass units