Methods, apparatus and systems for processing of code that includes key fields having surrogate and extends relationships are described. In some embodiments, a method includes receiving a pattern language code having definitions of a number of classes, wherein a definition of a first class of the number of classes comprises a reference to a field. The method also includes compiling the pattern language code to generate an object code, wherein the compiling comprises validating that the field is defined with a context of the first class. The context includes a second class of the number of classes that has a surrogate relationship with the first class.