working with mibs arbitrary indexes

Hi, I'm already collecting SNMP data from tables with arbitrary indexes (via opennms), however I have a question towards graphing my data. Each of my table index is a sequence of integers and each integer relates to a specific process. When I want to display  a graph of a row of such table, I need to choose one of the sequence of integers I used as index. Does rrd offer some kind of "if else" structure so I can check the value of the index and display a related string as a label???  I know I can change the index of the table and use strings instead of integers, but I prefer not to. Thanks in advance,