+ <STRONG>o</STRONG> pads, soft-keys were added in SVr3, and
+
+ Goodheart did not mention the background character or the <STRONG>cchar_t</STRONG> type.
+ Those are respectively SVr4 and X/Open features. He did mention the <STRONG>A_</STRONG>
+ constants, but did not indicate their values. Those were not the same
+ in different systems, even for those marked as System V.
+
+ Different Unix systems used different sizes for the bit-fields in
+ <STRONG>chtype</STRONG> for <EM>characters</EM> and <EM>colors</EM>, and took into account the different
+ integer sizes (32-bit versus 64-bit).
+
+ This table showing the number of bits for <STRONG>A_COLOR</STRONG> and <STRONG>A_CHARTEXT</STRONG> was
+ gleaned from the curses header files for various operating systems and
+ architectures. The inferred architecture and notes reflect the format
+ and size of the defined constants as well as clues such as the
+ alternate character set implementation. A 32-bit library can be used
+ on a 64-bit system, but not necessarily the reverse.
+
+ <STRONG>Bits</STRONG>
+ <STRONG>Year</STRONG> <STRONG>System</STRONG> <STRONG>Arch</STRONG> <STRONG>Color</STRONG> <STRONG>Char</STRONG> <STRONG>Notes</STRONG>
+ ------------------------------------------------------------------------
+ 1992 Solaris 5.2 32 6 17 SVr4 <EM>curses</EM>
+ 1992 HP-UX 9 32 no 8 SVr2 <EM>curses</EM>
+ 1992 AIX 3.2 32 no 23 SVr2 <EM>curses</EM>
+ 1994 OSF/1 r3 32 no 23 SVr2 <EM>curses</EM>
+ 1995 HP-UX 10.00 32 6 16 SVr3 <EM>curses</EM><STRONG>_</STRONG><EM>colr</EM>
+ 1995 HP-UX 10.00 32 6 8 SVr4, X/Open <EM>curses</EM>
+ 1995 Solaris 5.4 32/64 7 16 X/Open <EM>curses</EM>
+ 1996 AIX 4.2 32 7 16 X/Open <EM>curses</EM>
+ 1996 OSF/1 r4 32 6 16 X/Open <EM>curses</EM>
+ 1997 HP-UX 11.00 32 6 8 X/Open <EM>curses</EM>
+ 2000 U/Win 32/64 7/31 16 uses <EM>chtype</EM>
+
+ Notes:
+
+ Regarding HP-UX,
+
+ <STRONG>o</STRONG> HP-UX 10.20 (1996) added support for 64-bit PA-RISC processors
+ in 1996.
+
+ <STRONG>o</STRONG> HP-UX 10.30 (1997) marked "curses_colr" obsolete. That version
+ of curses was dropped with HP-UX 11.30 in 2006.
+
+ Regarding OSF/1 (and Tru64),
+
+ <STRONG>o</STRONG> These used 64-bit hardware. Like <EM>ncurses</EM>, the OSF/1 curses
+ interface is not customized for 32-bit and 64-bit versions.
+
+ <STRONG>o</STRONG> Unlike other systems which evolved from AT&T code, OSF/1
+ provided a new implementation for X/Open curses.
+
+ Regarding Solaris,
+
+ <STRONG>o</STRONG> The initial release of Solaris was in 1992.
+
+ <STRONG>o</STRONG> The <EM>xpg4</EM> (X/Open) curses was developed by MKS from 1990 to 1995.
+ Sun's copyright began in 1996.
+
+ <STRONG>o</STRONG> Sun updated the X/Open curses interface after 64-bit support was
+ introduced in 1997, but did not modify the SVr4 curses
+ interface.
+
+ Regarding U/Win,
+
+ <STRONG>o</STRONG> Development of the curses library began in 1991, stopped in
+ 2000.
+
+ <STRONG>o</STRONG> Color support was added in 1998.
+
+ <STRONG>o</STRONG> The library uses only <STRONG>chtype</STRONG> (no <STRONG>cchar_t</STRONG>).
+
+ Once X/Open curses was adopted in the mid-1990s, the constraint of a
+ 32-bit interface with many colors and wide-characters for <STRONG>chtype</STRONG> became
+ a moot point. The <STRONG>cchar_t</STRONG> structure (whose size and members are not
+ specified in X/Open Curses) could be extended as needed.
+
+ Other interfaces are rarely used now:
+
+ <STRONG>o</STRONG> BSD curses was improved slightly in 1993/1994 using Keith Bostic's
+ modification to make the library 8-bit clean for <STRONG>nvi(1)</STRONG>. He moved
+ <EM>standout</EM> attribute to a structure member.
+
+ The resulting 4.4BSD curses was replaced by <EM>ncurses</EM> over the next
+ ten years.
+
+ <STRONG>o</STRONG> U/Win is rarely used now.