Over the last decade, the prominence of statistical NLP applications that use syntactic rather than only word-based shallow clues increased very significantly. This prominence triggered the creation of large scale treebanks, i.e., corpora annotated with syntactic structures. However, a look at the annotation schemata used across these treebanks raises some issues. Thus, it is often unclear how the set of syntactic relation labels has been obtained and how it can be organized so as to allow for different levels of granularity in the annotation. Furthermore, it appears questionable that despite the linguistic insight that syntax is very much language-specific, multilingual treebanks often draw upon the same schemata, with little consideration of the syntactic idiosyncrasies of the languages involved. Our objective is to detail the procedure for establishing an annotation schema for surface-syntactic annotation of Spanish and present a restricted set of easy-to-use criteria and a methodology which facilitate the decision process of the annotators, but which can also accommodate for the elaboration of a more or a less fine-grained tagset. The procedure has been tested on a Spanish 3,513 sentence corpus, a fragment of the AnCora newspaper corpus.