IDA Help: set_segm_attr

set segment attribute
     arguments:      segea - any address within segment
                     attr  - one of SEGATTR_... constants
Please note that not all segment attributes are modifiable.
Also some of them should be modified using special functions
like set_segm_addressing, etc.

success set_segm_attr(long segea, long attr, long value);

#ifndef __EA64__
#define SEGATTR_START    0      // starting address
#define SEGATTR_END      4      // ending address
#define SEGATTR_ORGBASE 16
#define SEGATTR_ALIGN   20      // alignment
#define SEGATTR_COMB    21      // combination
#define SEGATTR_PERM    22      // permissions
#define SEGATTR_BITNESS 23      // bitness (0: 16, 1: 32, 2: 64 bit segment)
                                // Note: modifying the attrbite directly does
                                // not lead to the reanalysis of the segment.
                                // Using set_segm_addressing() is more correct.
#define SEGATTR_FLAGS   24      // segment flags
#define SEGATTR_SEL     28      // segment selector
#define SEGATTR_ES      32      // default ES value
#define SEGATTR_CS      36      // default CS value
#define SEGATTR_SS      40      // default SS value
#define SEGATTR_DS      44      // default DS value
#define SEGATTR_FS      48      // default FS value
#define SEGATTR_GS      52      // default GS value
#define SEGATTR_TYPE    96      // segment type
#define SEGATTR_COLOR   100     // segment color
#else
#define SEGATTR_START    0
#define SEGATTR_END      8
#define SEGATTR_ORGBASE 32
#define SEGATTR_ALIGN   40
#define SEGATTR_COMB    41
#define SEGATTR_PERM    42
#define SEGATTR_BITNESS 43
#define SEGATTR_FLAGS   44
#define SEGATTR_SEL     48
#define SEGATTR_ES      56
#define SEGATTR_CS      64
#define SEGATTR_SS      72
#define SEGATTR_DS      80
#define SEGATTR_FS      88
#define SEGATTR_GS      96
#define SEGATTR_TYPE    184
#define SEGATTR_COLOR   188
#endif

// Segment permissions
#define SEGPERM_EXEC  1         // Execute
#define SEGPERM_WRITE 2         // Write
#define SEGPERM_READ  4         // Read
#define SEGPERM_MAXVAL (SEGPERM_EXEC + SEGPERM_WRITE + SEGPERM_READ)

// Valid segment flags
#define SFL_COMORG   0x01       // IDP dependent field (IBM PC: if set, ORG directive is not commented out)
#define SFL_OBOK     0x02       // orgbase is present? (IDP dependent field)
#define SFL_HIDDEN   0x04       // is the segment hidden?
#define SFL_DEBUG    0x08       // is the segment created for the debugger?
#define SFL_LOADER   0x10       // is the segment created by the loader?
#define SFL_HIDETYPE 0x20       // hide segment type (do not print it in the listing)