Does a BMW 3-series engine have a timing belt or chain?

Although the year, specific model, and engine size is not stated in the question, here are some general guidelines:

All the 4 cylinder BMW 3-series (318i, 320i) had a timing chain.

From 1984 to 1991, the 6 cyl (325 series) had a timing belt.

From 1992 and up, the 6 cyl (323, 325, 328, 335 series) had a timing chain.