Syntax
anEscapedString = aString.escapeURI(codepage)
anEscapedString = escapeURI(LITERAL, codepage)
Semantics

The string is escaped to conform with URI encoding as defined in RFC 2396. The codepage defines the target encoding, e.g. Web forms accept parameters in the same encoding as the website (e.g. ISO-8859-1). The return value is a string.

Parameters of URLs must be encoded value by value.

SubstitutablesaString Can be any variable or object attribute having the type String.  
codepage A string with the name of the target codepage.
LITERAL String literal.
Examples
set escaped = concat("http://www.e2e.ch/?name=", escapeURI("Müller", "iso-8859-1"));
The string escaped will have the value http://www.e2e.ch/?name=M%fcller .

Example File (Builder project Basic Modeling/Data):

<your example path>\Basic Modeling\Data\uml\urlEncoding.xml