The following words and terms when used in this subchapter shall have the following meanings unless the context clearly indicates otherwise:(1) Financial assurance--A financial instrument that as provided by rules adopted by the TCEQ may be used to comply with financial responsibility requirements established under the Water Code §26.352.(2) Insurer--An entity operating under the Insurance Code providing insurance or other financial assurance to an owner or operator of underground storage tanks for the purposes of meeting financial responsibility requirements established under the Water Code §26.352, including all entities operating under the Insurance Code Chapters 941 (Lloyd's plans), 942 (reciprocals and interinsurance exchanges), 981 (surplus lines insurers), and 2201 (risk retention groups and purchasing groups).(3) TCEQ--Texas Commission on Environmental Quality.