significant inside strings.
Strings can be concatenated using @samp{+}, so that @samp{"a" + 'b' +
-'c'} is equivalent to @samp{'abc'}. Concatenation is useful for
-splitting a single string across multiple source lines.
-
-Strings may also be expressed as hexadecimal, octal, or binary
-character values by prefixing the initial quote character by @samp{X},
-@samp{O}, or @samp{B} or their lowercase equivalents. Each pair,
-triplet, or octet of characters, according to the radix, is
-transformed into a single character with the given value. If there is
-an incomplete group of characters, the missing final digits are
-assumed to be @samp{0}. These forms of strings are nonportable
-because numeric values are associated with different characters by
-different operating systems. Therefore, their use should be confined
-to syntax files that will not be widely distributed.
-
-@cindex characters, reserved
-@cindex 0
-@cindex white space
-The character with value 00 is reserved for
-internal use by PSPP. Its use in strings causes an error and
-replacement by a space character.
+'c'} is equivalent to @samp{'abc'}. So that a long string may be
+broken across lines, a line break may precede or follow, or both
+precede and follow, the @samp{+}. (However, an entirely blank line
+preceding or following the @samp{+} is interpreted as ending the
+current command.)
+
+Strings may also be expressed as hexadecimal character values by
+prefixing the initial quote character by @samp{x} or @samp{X}.
+Regardless of the syntax file or active dataset's encoding, the
+hexadecimal digits in the string are interpreted as Unicode characters
+in UTF-8 encoding.
+
+Individual Unicode code points may also be expressed by specifying the
+hexadecimal code point number in single or double quotes preceded by
+@samp{u} or @samp{U}. For example, Unicode code point U+1D11E, the
+musical G clef character, could be expressed as @code{U'1D11E'}.
+Invalid Unicode code points (above U+10FFFF or in between U+D800 and
+U+DFFF) are not allowed.
+
+When strings are concatenated with @samp{+}, each segment's prefix is
+considered individually. For example, @code{'The G clef symbol is:' +
+u"1d11e" + "."} inserts a G clef symbol in the middle of an otherwise
+plain text string.
@item Punctuators and Operators
@cindex punctuators
one that consists only of white space or comments, also ends a command.
@node Syntax Variants
-@section Variants of syntax.
+@section Syntax Variants
@cindex Batch syntax
@cindex Interactive syntax
-There are two variants of command syntax, @i{viz}: @dfn{batch} mode and
-@dfn{interactive} mode.
-Batch mode is the default when reading commands from a file.
-Interactive mode is the default when commands are typed at a prompt
-by a user.
-Certain commands, such as @cmd{INSERT} (@pxref{INSERT}), may explicitly
-change the syntax mode.
-
-In batch mode, any line that contains a non-space character
-in the leftmost column begins a new command.
-Thus, each command consists of a flush-left line followed by any
-number of lines indented from the left margin.
-In this mode, a plus or minus sign (@samp{+}, @samp{@minus{}}) as the
-first character in a line is ignored and causes that line to begin a
-new command, which allows for visual indentation of a command without
-that command being considered part of the previous command.
-The period terminating the end of a command is optional but recommended.
-
-In interactive mode, each command must be terminated with a period
-or by a blank line.
-The use of @samp{+} and @samp{@minus{}} as continuation characters is not
-permitted.
+There are three variants of command syntax, which vary only in how
+they detect the end of one command and the start of the next.
+
+In @dfn{interactive mode}, which is the default for syntax typed at a
+command prompt, a period as the last non-blank character on a line
+ends a command. A blank line also ends a command.
+
+In @dfn{batch mode}, an end-of-line period or a blank line also ends a
+command. Additionally, it treats any line that has a non-blank
+character in the leftmost column as beginning a new command. Thus, in
+batch mode the second and subsequent lines in a command must be
+indented.
+
+Regardless of the syntax mode, a plus sign, minus sign, or period in
+the leftmost column of a line is ignored and causes that line to begin
+a new command. This is most useful in batch mode, in which the first
+line of a new command could not otherwise be indented, but it is
+accepted regardless of syntax mode.
+
+The default mode for reading commands from a file is @dfn{auto mode}.
+It is the same as batch mode, except that a line with a non-blank in
+the leftmost column only starts a new command if that line begins with
+the name of a PSPP command. This correctly interprets most valid PSPP
+syntax files regardless of the syntax mode for which they are
+intended.
+
+The @option{--interactive} (or @option{-i}) or @option{--batch} (or
+@option{-b}) options set the syntax mode for files listed on the PSPP
+command line. @xref{Main Options}, for more details.
@node Types of Commands
@section Types of Commands
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