FEATURES
********

  o plot(merge(x1, x2)) can generate NAs in x1 or x2 which results in
    line breaks in the plot.  Even plot(x) may result in an empty plot
    if there are no adjacent non-NAs.  Need some way of distinguishing
    between structurally and non-structurally missing items.  Perhaps
    just an argument that can be set to ignore NAs connecting 
    successive non-NAs.

  o incorporate runmean in package caMassClass
 
  o allow lag(z, k) to take a vector k. (Look at naming of columns...)

  o allow log to be specified per plot in plot.zoo
  
  o performance enhancement when using arithmetic on zoo objects. Check
    if they have same index first.

  o speedup for indexing strictly regular series. Test with is.regular first.
	set.seed(1)

	x <- ts(rnorm(5000))
	xz <- as.zoo(x)
	system.time({  ################################
	  for(i in 1:5000) if (is.regular(x)) 
		x[(i - tsp(x)[1])*frequency(x) + 1] <- 0
	else
		window(xz, start = i, end = i) <- 0
	},
	gc = TRUE)
	system.time( for (i in 1:5000) xz[I(i)] <- 0, gc = TRUE )
	system.time( for (i in 1:5000) window(xz, start=i, end=i) <- 0, 
		gc = TRUE 

  o zoo()
    - support zoo data.frame objects (and zoo list objects)
    - fully support zoo factor objects [limited support already 
      available]
    - idea: new class "Zoo" that is not a matrix plus attribute
            but a list with slots "coredata", "index" and "frequency". 
    
  o merge()
    - names not processed correctly when retclass = "list"

        
  o misc functions
    - interface to additional statistical routines such as the ones
      referenced in:
      http://CRAN.R-project.org/doc/contrib/Ricci-refcard-ts.pdf
      [Z: with as.ts.zoo() most of the functions work directly
       by coercing the first argument to "ts"]


  o QA
    - regression test suite
    - additional use and testing



INTERFACES
**********

  o provide fCalendar interface routine to the Rmetrics projects



DOCUMENTATION & COMMUNICATION
*****************************

  o R news article based on the vignette

  o some data to include with zoo

  o more examples for the help files

  o FAQ
