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Dear list, consider the following sample: \setuppapersize[A8] \starttext \ConTeXt: \in[seac] Is it defined?: \doifelse{\in[seac]}{??}{undefined}{defined} \Lua: \ctxlua{context([[{\in[seac]}]])} Is it defined?: \startlua if [[{\in[seac]}]] == "??" then context("undefined") else context("defined") end \stoplua \stoptext Is there a way to deal with undefined references? I mean, I need a conditional to handle undefined references. Why do I have undefined references in my documents? Well, I have almost 90 (Markdown) documents that I need to compile as single documents and also as one document. When compiling as single documents, there are a few references to other documents. This is the reason why they are undefined. Any chance to be able to catch a "??" output (or \dummyreference) from "\in[reference]"? Many thanks for your help, Pablo -- http://www.ousia.tk