The "fossilized binding" for a component is a snapshot of the evaluated value of the value binding EL at the time that the component tree for the View was produced, as well as other contextual information which lets the submitted native component value be correctly processed. This is implemented (by the default HTML RenderSystem) as a mirror "hidden field" appended to the parent form of the tag peering the component, which stores the information sufficient to, at the time of the following POST

1. Determine the old value for a component, as compared to the submitted value at the POST, and
2. Determine the EL l-value that should be used to resolve the setter for the new submitted value.

Once decoded, a binding is stored in a value type SubmittedValueEntry, which will be stored in the RSVC for the current request. From there the processing pipeline reshapes it to form a DataAlterationRequest, in which form it is directly applied to the bean model. The decoding and encoding of bindings to and from String key/value pairs is determined and documented in the class FossilizedConverter.java. - in general, the fossilized binding for a component with ID componentid, an EL value binding of #bean.member and an old value of oldvalue is

key = componentid-fossil, value=[i|o]uitype-name#{bean.member}oldvalue

The character key i/o represents whether the native component is expected to submit a value or not, and the uitype-name is the name of the UIType of the native submission type.

For example, the following HTML <select> component

<select name="fontFace-selection" id="fontFace-selection">

<input type="hidden" name="fontFace-selection-fossil" 
                      value="istring#{preferencesBean.fontFace}" />