Analysis of massive codebases ("big code") presents an opportunity for drawing insights about programming practice and enabling code reuse. One of the main challenges in analyzing big code is finding a representation that captures sufficient semantic information, can be constructed efficiently, and is amenable to meaningful comparison operations. We present a formal framework for representing code in large codebases. In our framework, the semantic descriptor for each code snippet is a partial temporal specification that captures the sequences of method invocations on an API. The main idea is to represent partial temporal specifications as symbolic automata-automata where transitions may be labeled by variables, and a variable can be substituted by a letter, a word, or a regular language. Using symbolic automata, we construct an abstract domain for static analysis of big code, capturing both the partialness of a specification and the precision of a specification. We show interesting relationships between lattice operations of this domain and common operators for manipulating partial temporal specifications, such as building a more informative specification by consolidating two partial specifications, and comparing partial temporal specifications.