This paper describes the CTB Coreference Annotation Guidelines for annotating pronominal anaphoric expressions in the Penn Chinese Treebank. The goals of the annotation are: to provide training data for learning-based pronoun resolution tools, and to provide a "gold" standard to be used in the evaluation of pronoun resolution algorithms. The choices that were made concerning the coindexing of pronominal anaphors and their antecedents are discussed, as are some questions that arose in trying to categorize those pronominal expressions that did not refer to specific nominal entities in the text.