\environment environment

\startproduct product

\startfrontmatter

\completecontent

\stopfrontmatter

\startbodymatter

\startpart[reference=sec:zero,title=Product]

\dontleavehmode\reference[ref:zero]{Thuan}%
\input thuan

\component component-1
\component component-2

\stoppart

\stopbodymatter

\stopproduct