[...]

In addition, expansion of batch script argument references (%0, %1, etc.) have been changed as follows:

%* in a batch script refers to all the arguments (e.g. %1 %2 %3 %4 %5 …)

Substitution of batch parameters (%n) has been enhanced.  You can
now use the following optional syntax:

%~1         – expands %1 removing any surrounding quotes (“)
%~f1        – expands %1 to a fully qualified path name
%~d1        – expands %1 to a drive letter only
%~p1        – expands %1 to a path only
%~n1        – expands %1 to a file name only
%~x1        – expands %1 to a file extension only
%~s1        – expanded path contains short names only
%~a1        – expands %1 to file attributes
%~t1        – expands %1 to date/time of file
%~z1        – expands %1 to size of file
%~$PATH:1   – searches the directories listed in the PATH
environment variable and expands %1 to the fully
qualified name of the first one found.  If the
environment variable name is not defined or the
file is not found by the search, then this
modifier expands to the empty string

The modifiers can be combined to get compound results:

%~dp1       – expands %1 to a drive letter and path only
%~nx1       – expands %1 to a file name and extension only
%~dp$PATH:1 – searches the directories listed in the PATH
environment variable for %1 and expands to the
qualified name of the first one found.  If the
environment variable name is not defined or the
file is not found by the search, then this
modifier expands to the empty string

The modifiers can be combined to get compound results:

%~dp1       – expands %1 to a drive letter and path only
%~nx1       – expands %1 to a file name and extension only
%~dp$PATH:1 – searches the directories listed in the PATH
environment variable for %1 and expands to the
drive letter and path of the first one found.
%~ftza1     – expands %1 to a DIR like output line

In the above examples %1 and PATH can be replaced by other
valid values.  The %~ syntax is terminated by a valid argument
number.  The %~ modifiers may not be used with %*

I bet the guy meant %~dp0 in the call to cacls