Enthalpies are always derived from a set of reference species, so without a common set of references, the values of enthalpies are meaningless. When building microkinetic models, we are not only interested in the enthalpies or Gibbs free energies of a single species but rather the entire reaction pathway or mechanism. In heterogeneous catalysis, this includes the adsorption of gas-phase reactants, a series of surface reaction steps, and the desorption of gas-phase products. Thus, it is necessary to align the enthalpies of all species to the same set of reference species, which creates a thermochemical network. In this work, we introduce the term anchor species as a special case of these reference species that form the basis of a thermochemical network. The introduction of this term helps to resolve ambiguity in approaches where multiple or non-standard references are used. As we will show, the anchor species of a thermochemical network will have a relative enthalpy of zero within their own reference frame. In contrast, reference species may have zero or non-zero values.