def xf_used_attr
atr_num = num_format & 1
atr_fnt = font_index & 1
atr_fnt = 1 unless @format.font.color == :text
atr_alc = 0
if horizontal_align != 0 \
|| vertical_align != 2 \
|| indent_level > 0 \
|| shrink? || merge_range? || text_wrap?
then
atr_alc = 1
end
atr_bdr = 1
atr_pat = 0
if @format.pattern_fg_color != :border \
|| @format.pattern_bg_color != :pattern_bg \
|| pattern != 0x00
then
atr_pat = 1
end
atr_prot = hidden? || locked? ? 1 : 0
attrs = atr_num
attrs |= atr_fnt << 1
attrs |= atr_alc << 2
attrs |= atr_bdr << 3
attrs |= atr_pat << 4
attrs |= atr_prot << 5
attrs << 2
end