In your post, you confuse "being liberal" with "not being explicit". You can be liberal, but explicit if you put enough intelligence in the explicit description.

E.g., COBOL is a very non-liberal language, while ANSI C is a fairly liberal language in comparison, while still being perfectly explicit about what it will accept. Or take JCL, the job command language on most mainframes, and compare it with the POSIX standard "sh" shell implementation. Both are explicit, but the "sh" shell is much more liberal in what it accepts.

If talking about languages, being liberal while being strict is often called "expressive".

Christian Lemburg
Brainbench MVP for Perl
http://www.brainbench.com