comparing isDate() vs isValid("date")

isDate_vs_isValid.cfm

<cfscript>

	variables.foo = 0;

	writeDump("isDate(): " & isDate(variables.foo)); //returns false
		writeoutput("<br />");

	writeDump("isValid('date'): " & isValid("date",variables.foo)); //returns true
		writeoutput("<br />");

	writeDump("isNumericDate(): " & isNumericDate(variables.foo)); //returns true
		writeoutput("<br />");

	writeDump("dateFormat(): " & dateFormat(variables.foo,"yyyy-mm-dd")); //returns 1899-12-30
		writeoutput("<br />");

	//this one is just for fun
	writeDump("isDate(dateFormat(10000000,'yyyy-mm-dd')): " & isDate(dateFormat(10000000,"yyyy-mm-dd"))); //ACF10: returns no Railo 4.1: returns true
		writeoutput("<br />");

</cfscript>

<pre>
relevant documentation:

	https://learn.adobe.com/wiki/display/coldfusionen/IsDate
	https://learn.adobe.com/wiki/display/coldfusionen/IsNumericDate
	https://learn.adobe.com/wiki/display/coldfusionen/IsValid
		"date or time: any date-time value, including dates or times; equivalent to the IsDate function."

	http://railodocs.org/index.cfm/function/isvalid
		"date or time: any date-time value, including dates or times; equivalent to the IsDate function."

	Conclusion: I believe this is at least a documentation bug with isValid("date",) - it is equivalent to 
		isNumericDate() not isDate(). Would like confirmation on this from ACF and Railo.

		I also feel that isNumericDate()'s documentation would benefit from describing the valid range of 
		numbers that could be provided as well as describing what the numbers correspond to, 
		eg 0 = 1899-12-30. 

		I also would like isDate() to list the valid date formats that it accepts.
</pre>