Syntax Encoding Schemes (SES) are the rules that specify how a value has to be structured. Dublin Core defined Syntax Encoding Schemes as DCMI Metadata Terms - e.g. dcterms:W3CDTF for date specification. The relationship between Dublin Core datatypes and properties is as follows:
Certain properties - e.g. date, identifier, etc. - may be typed by a Syntax Encoding Scheme, where the Syntax Encoding Scheme dictates the syntax of the values used with that property.
Source: Dublin Core