with referents-not-allowed (with open-modifier (& open-modifier))+ | with open-modifier)*

This open modifier is the default for most streams. It does not allow referents to be attached to the stream, and any attempt to write a referent to the stream is a fatal error, regardless of whether the referent has a current value.

The only streams for which this modifier is not the default are:

• #main-output
• #suppress
• #error