Understanding Metamodel.Enrichment.MOStrategy in RBDO using PCE Metamodel


I am working with RBDO surrogate models using Polynomial Chaos Expansion (PCE), and I came across an example in the UQLab documentation that includes the following code line:

RBDO_PCEOpts.Metamodel.Enrichment.MOStrategy = 'mean';

However, I couldn’t find any detailed explanation about what this MOStrategy does in the UQLab documentation.

Could you please clarify the purpose and function of the Metamodel.Enrichment.MOStrategy in the context of PCE metamodels for RBDO?