Today, most web browsers are Standards mode compliant, which means that they strictly comply with W3C and IETF standards in standards mode. Internet Explorer offers also the Quirks mode, which is a rendering mode used for the sake of maintaining backward compatibility with web pages designed for Internet Explorer 5 and earlier.
When raising the words “Standards mode” or “Quirks mode” questions never end … There is already a very thorough blog clarifying issues with best recommended solutions for the Enterprise Portal (see reference here). In this blog I will focus on specific information related to Standards and Quirks in Fiori Launchpad on Portal (FLP on EP) and on the different SAP UI technologies.
Fiori Framework Page works only with Standards mode since it is based on UI5 technology. There is no way for mixing different rendering (“document”) modes in same page, therefore all iViews that are rendered “in-place” should comply with standards mode (iView property “Default Document Rendering Mode” with value “Standards”).
For iViews that can’t render in Standards mode you should set the property “Launch in New Window” to “Display in Separate Headerless Portal Window” (nav mode 3). This navigation mode, as its name implies, tells the iView to open in a new window in Quirks mode.
In general, all Standards mode enabled applications can be opened in-place in FLP on EP, therefore applications, which are based on UI technologies that support Standards mode, can be opened in-place as well. Today most of SAP UI technologies support Standards mode. You can verify Standards mode support details and notes for each UI technology in PAM.
Another topic you should be aware of is that the support of standards mode by the UI technology does not necessarily mean that new themes (such as: sap_Corbu, sap_blueCrystal and sap_belize) are supported. It could be that old UI technologies (such as HTMLB, BI and BSP), which support standards mode, are based on UR classic. Although the controls of UR classic, used by these applications, were qualified to support Standards mode, UR Classic doesn’t support new themes, therefore these applications are bounded to this limitation as well (see Note 2124106 – Themes for Unified Rendering based UI technologies). In such cases you can always adapt the visual appearance (e.g. by changing colors, background etc.) and reduce visual theme dissimilarities by creating a custom Fallback Theme.