WMS image format (use 'image/png' for layers with transparency).
Default value: false.
(required) Comma-separated list of WMS layers to show.
Default value: ''.
Comma-separated list of WMS styles.
Default value: 'image/jpeg'.
If true, the WMS service will return images with transparency.
Default value: '1.1.1'.
Version of the WMS service to use.