Format (.I) instances of type "double".

man3/atof.3

@@ -39,7 +39,8 @@ atof \- convert a string to a double
 The
 .BR atof ()
 function converts the initial portion of the string
-pointed to by \fInptr\fP to double.
+pointed to by \fInptr\fP to
+.IR double .
 The behavior is the same as
 .sp
 .RS

man3/difftime.3

@@ -38,7 +38,8 @@ difftime \- calculate time difference
 The
 .BR difftime ()
 function returns the number of seconds elapsed
-between time \fItime1\fP and time \fItime0\fP, represented as a double.
+between time \fItime1\fP and time \fItime0\fP, represented as a
+.IR double .
 The two times are specified in calendar time, which represents the time
 elapsed since the Epoch
 (00:00:00 on January 1, 1970, Coordinated Universal Time (UTC)).

man3/ecvt.3

@@ -52,7 +52,8 @@ The
 .BR ecvt ()
 function converts \fInumber\fP to a null-terminated
 string of \fIndigits\fP digits (where \fIndigits\fP is reduced to an
-system-specific limit determined by the precision of a double),
+system-specific limit determined by the precision of a
+.IR double ),
 and returns a pointer to the string.
 The high-order digit is non-zero, unless
 .I number

man3/nextafter.3

@@ -53,7 +53,9 @@ The
 .BR nexttoward ()
 functions do the same as the
 .BR nextafter ()
-functions, except that they have a long double second argument.
+functions, except that they have a
+.I "long double"
+second argument.
 .PP
 These functions will signal overflow or underflow if the result
 goes outside of the range of normalized numbers.

man3/strfmon.3

@@ -105,12 +105,14 @@ The three conversion characters are
 Put a '%' character in the result string.
 .TP
 .B i
-One argument of type double is converted using the locale's
-international currency format.
+One argument of type
+.I double
+is converted using the locale's international currency format.
 .TP
 .B n
-One argument of type double is converted using the locale's
-national currency format.
+One argument of type
+.I double
+is converted using the locale's national currency format.
 .SH "RETURN VALUE"
 The
 .BR strfmon ()