_dta:
  1.  date_changes20182 set up by Jean Roth , jroth@nber.org , 9 Feb 2018
  2.  NBER URL: http://www.nber.org/data/ndc-hcpcs-crosswalk-dme.html
  3.  Source Page: https://www.dmepdac.com/crosswalk/index.html
      https://www.dmepdac.com/crosswalk/2018.html

ndc:
  1.  The National Drug Code (NDC) serves as a universal product identifier for human
      drugs and biologics.
  2.  Each NDC must be reported as an 11-digit code unique to the manufacturer of the
      specific drug or product.

ndc13:
  1.  The National Drug Code (NDC) serves as a universal product identifier for human
      drugs and biologics.
  2.  Each NDC must be reported as an 11-digit code unique to the manufacturer of the
      specific drug or product.

  obs:            24                          
 vars:             5                          9 Feb 2018 15:56
 size:         1,056                          (_dta has notes)
-----------------------------------------------------------------------------------------
              storage   display    value
variable name   type    format     label      variable label
-----------------------------------------------------------------------------------------
ndc             str11   %11s                * National Drug Code (NDC)
ndc13           str13   %13s                * National Drug Code (NDC) with Dashes
change          str17   %17s                  Change
olddate         byte    %td..                 Old Date
newdate         int     %td..                 New Date
                                            * indicated variables have notes
-----------------------------------------------------------------------------------------
Sorted by: ndc