[dd260aaf72] Allow the -dictionary option to be read from a pushed transform.

1 files changed, 12 insertions, 6 deletions

diff --git a/doc/zlib.n b/doc/zlib.n
index 9f3078d..fd29e0d 100644
--- a/doc/zlib.n
+++ b/doc/zlib.n
@@ -174,7 +174,11 @@ to the \fBzlib push\fR command:
 .VS "TIP 400"
 Sets the compression dictionary to use when working with compressing or
 decompressing the data to be \fIbinData\fR. Not valid for transformations that
-work with gzip-format data.
+work with gzip-format data.  The dictionary should consist of strings (byte
+sequences) that are likely to be encountered later in the data to be compressed,
+with the most commonly used strings preferably put towards the end of the
+dictionary. Tcl provides no mechanism for choosing a good such dictionary for
+a particular data sequence.
 .VE
 .TP
 \fB\-header\fI dictionary\fR
@@ -207,11 +211,13 @@ compression algorithm depends on what format is being produced or consumed.
 .TP
 \fB\-dictionary\fI binData\fR
 .VS "TIP 400"
-This read-write options gets or sets the compression dictionary to use when
-working with compressing or decompressing the data to be \fIbinData\fR. It is
-not valid for transformations that work with gzip-format data, and should not
-normally be set on compressing transformations other than at the point where
-the transformation is stacked.
+This read-write options gets or sets the initial compression dictionary to use
+when working with compressing or decompressing the data to be \fIbinData\fR.
+It is not valid for transformations that work with gzip-format data, and should
+not normally be set on compressing transformations other than at the point where
+the transformation is stacked. Note that this cannot be used to get the
+current active compression dictionary mid-stream, as that information is not
+exposed by the underlying library.
 .VE
 .TP
 \fB\-flush\fI type\fR