You can pass your DSL definitions in as many files as you like. As for expansion, the "expander" statement has no effect: the DSL expander of a KnowledgeBuilder always uses all DSL definitions it has been fed prior to the DSLR. To use separate DSL definitions for different DSLRs, you should use different KnowledgeBuilders to avoid cross-fire. For splitting DSL files, note that the order of DSL entries matters. There is no point in keeping a DSL file as a binary object, and therefore there's no way of doing that. But you can serialize the expanded and compiled DSLRs as serialized KnowledgePackages. All of this is valid for >= 5.1.x. -W On 4 February 2011 05:33, Bala <bala.ganesh(a)accenture.com&gt; wrote: