get an argument and add a 'age' field to the struct

docs/libcurl/curl_version_info.3

@@ -2,17 +2,23 @@
 .\" nroff -man [file]
 .\" $Id$
 .\"
-.TH curl_version_info 3 "25 Sep 2002" "libcurl 7.10" "libcurl Manual"
+.TH curl_version_info 3 "30 Sep 2002" "libcurl 7.10" "libcurl Manual"
 .SH NAME
 curl_version_info - returns run-time libcurl version info
 .SH SYNOPSIS
 .B #include <curl/curl.h>
 .sp
-.BI "curl_version_info_data *curl_version_info( );"
+.BI "curl_version_info_data *curl_version_info( CURLversion "type ");"
 .ad
 .SH DESCRIPTION
 Returns a pointer to a filled in struct with information about various
-run-time features in libcurl.
+run-time features in libcurl. \fItype\fP should be set to the version of this
+functionality by the time you write your program. This way, libcurl will
+always return a proper struct that your program understands, while programs in
+the future might get an different struct. CURLVERSION_NOW will be the most
+recent one for the library you have installed:
+
+        data = curl_version_info(CURLVERSION_NOW);
 
 Applications should use this information to judge if things are possible to do
 or not, instead of using compile-time checks, as dynamic/DLL libraries can be
@@ -22,6 +28,7 @@ The curl_version_info_data struct looks like this
 
 .nf
 typedef struct {
+  CURLversion age;          /* 0 - this kind of struct */
   const char *version;      /* human readable string */
   unsigned int version_num; /* numeric representation */
   const char *host;         /* human readable string */
@@ -33,6 +40,11 @@ typedef struct {
 } curl_version_info_data;
 .fi
 
+\fIage\fP describes what kind of struct this is. It is always 0 now. In a
+future libcurl, if this struct changes, this age counter may be increased, and
+then the struct for number 1 will look different (except for this first struct
+field).
+
 \fIversion\fP is just an ascii string for the libcurl version.
 
 \fIversion_num\fP is a 6 digit hexadecimal number created like this: <2 digits