What does EN 14781 certificate mean? This is a old (replaced by another certificate around 2014; ISO something) certificate for racing bikes given by European Committee of Standardization. (EN 1xxxx for another types). But what does this cert mean? If my bike has this cert, does this mean -my bike is a racing bike- or -my bike has a safety level of racing bikes standards-.
The British Standards Institute provides the following summary:

BS EN 14781:2005 covers the test methods applicable in the design and manufacture of racing bikes.  It was developed to ensure the strength and durability of individual parts as well as of the bicycle as a whole, demanding high quality throughout and consideration of safety aspects from the design stage onwards.
This European Standard specifies safety and performance requirements for the design, assembly and testing of racing bicycles and sub-assemblies, and lays down guidelines for manufactures instructions on the use and care of such bicycles.
BS EN 14781:2005 applies to racing bicycles intended for high-speed amateur use on public roads, and on which the saddle can be adjusted to provide a maximum saddle height of 635 mm or more.
This European Standard does not apply to mountain bicycles and to specialised types of racing bicycle such as tandems or bicycles designed and equipped for use in sanctioned competitive events.
For bicycles with a saddle height of ≤ 435 mm see EN 71 and with a maximum saddle height of more than 435 mm and less than 635 mm see EN 14765.

Standards documents themselves are usually rather expensive (£254 for this one, even though it's obsolete) so I doubt many here have access to the full text.