they can perform I/O using XMLHttpRequest (although the responseXML and channel attributes are always null) or fetch (with no such restrictions).

It is an isolated environment that is insulated from the window object, the document object, direct internet access

more difficult to maintain

make our components larger

convolute the code

Notes

All components will share the library code

Automatic linking of other resources and discussions

Portability across hosting services

Rich connections to other online resources

Discovery and linking of annotations across different content instances (html vs. pdf)

Rich

Many different clients that support basic functionality

Tags that help filter, sort, identify annotations by date, relevance, topic…factual annotations vs. comments  (pragmatic vs. true semantic interoperability)

People identifiers within groups and globally (SSO including with ORCID), w/ Twitter, other SM groups

repositories

versions of content

Selection

ability to evolve permissions on selected annotations

branded

authoritative

private group

but