Tip: Looking for advice on site searching

[Bastiat]

Sorry for reviving an old thread from the Strategy Index, but I have the following question regarding site searching and Edi's incredibly valuable database:

The "Era" column says "applicable only for national sites". I'm assuming this means:

1. Anything without an Era tag can be spawned in any Era?

2. Sites with an Era tag can only spawn in Capitals, or is there some other meaning of "national sites"? I'm unsure of this because there seems to be far more "national sites" than "nations", but maybe each "nation" draws a random national site for its Capital.

Any insights? Thanks in advance.