Organisations that make use of technology for their internal and external operations, for gaining competitive advantages, are referred to as Digital Enterprises. Enterprise Modelling (EM) is the representation of a business organisation's (single or networked) structure and behaviour, to carry out analysis, (re-)design, and efficient optimisation of its operations. However, there are certain issues in the field of EM that create strategic challenges for digital enterprises currently, e.g. to determine the relationship and constraints between high level modelling and analytical modelling. A systematic literature review had been carried out to address this matter. Amongst others, this article highlights constraints that must be considered when developing process models and temporal logic. One step towards syntax generalisation of enterprise models is by viewing the enterprise from the perspective of the business services it uses and renders to its clients.