What this is doing is turning on the RewriteEngine so we can redirect url's nicely, then we are defining using the RewriteRule that /404/ or /404 should redirect to the custom 404 page. I then state that the ErrorDocument 404 and 403 should redirect to the 404 page. I do this for security so, a user does not know whether or not a file exists or if they just don't have access.

The lines between Microdata, RDFa, and JSON-LD are indeed currently very blurry and that there is still no widely accepted de facto among the three. This will have to wait for now. Perhaps a couple or more years. Meanwhile, Microdata should not be labeled with Schema.org like you mentioned because those two are different things.

Forum Standaardisatie Lijst open standaarden RDF RDF

RDFa：资源描述框架，是一种使用属性向网页中嵌入详细信息的标准。 优点：是一个稳定不变的标准。 缺点：1、RDFa最初是为XHTML设计的而不是HTML5，所以在严格的RDFa和松散的HTML5之间存在着争议。 2、RDFa很复杂，网页嵌入RDFa之后会显得笨重。

Aangezien RDFa andere standaarden ondersteunt die wel dit volwassenheidsniveau kennen (RDF / HTML / XML) en deze standaard een toegevoegde heeft ten aan zien van deze standaarden, is het advies om deze standaard op te nemen op de lijst met open standaarden met de status ‘aanbevolen’.

序列号要么用软件直接生成要么用数据库导入，如图所示：

Com RDFa, a estrutura equivalente seria algo como: ... Enquanto Microdata e RDFa exigem escrever junto ao HTML, que pode dificultar a implementação, o JSON-LD se destaca por separar os dados em uma tag distinta, facilitando o uso.

RDFa is an attempt to get both the flexibility of RDF and the simplicity of microformats. Microdata was a response to RDFa, but with a different data model (roughly arrays and hashes rather than a relational model). Unlike microformats neither dictate what sort of information is provided, just how it is encoded.

I have a quick question about RDFa and Microdata. My current understanding is that RDFa is RDF implemented into HTML but is complicated for new developers like myself, Microdata seems really easy ...

RDFa 1.1 extends HTML5 so that it’s valid to use meta and link elements in the body, as long as they contain a property attribute. You can use both ways, HTML5’s name and RDFa’s property, together on the same meta element.