punctuation mark "——"

[aboooot]

Dear friends,

what does this sign of punctuation "——" mean in Chinese?

Is it like ":"?

In this sentence

另外，由于关注和参与方面众多——政府、业主、设计、科研、监理、施工总包、各专业分包、材料及产品厂家等等，使得国家体育场工程上下游关系相互牵连影响、错综复杂。这都对国家体育场的项目设计组织和管理提出了严峻挑战和要求

is the list that follows "——" the list of 关注和参与的方面?

Does it mean that

the numerous aspects of interest concerned such as the government, the propietors, the design, the scientific research, the control, the main contractor, 各专业分包 (I don't know the meaning), the materials and the products factories made the vertical relationships of the National Stadium influence each other and intricated?

[monto]

Words after "——" explains or modifies the words before it.

So the function sometimes look like ", that is," or "i. e." and sometimes just like remarks.