how does it work ? if no schema location

Here is example of

Using property placeholders for any kind of attribute in the XML DSL
Available as of Camel 2.7

<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:prop="http://camel.apache.org/schema/placeholder"
xsi:schemaLocation=" http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans.xsd
http://camel.apache.org/schema/spring
http://camel.apache.org/schema/spring/camel-spring.xsd ">

my question is how could it work?
there is no schemaLocation of for the name space
(http://camel.apache.org/schema/placeholder)

any hints will be more than welcome! ?