Explanation:

• Abbreviations and symbols for engineering drawings are used to express and detail features of an engineering drawing.
• This contains abbreviations common to language of individuals who work in manufacture and inspection of parts and assemblies with engineering drawings.

Explanation:

Aligned Dimensioning:

1. The dimensions lines are drawn parallel to object lines.
2. The dimensions values are placed above dimensions lines and not by breaking dimensions lines.
3. The dimensions values are placed near middle and clear of dimensions lines.
4. All dimensions are so placed that y can be read from bottom or right hand edge of drawing sheet.
5. It is used in Engineering drawings.

Additional InformationUnidirectional Dimensioning:

1. The dimensions lines are drawn parallel to object lines. 
2. The horizontal lines are dimensioned as in above method.
3. Vertical and inclined lines are dimensioned by writing value of dimension in gap left in middle of dimensions lines.
4. All dimensions are so placed that y can be read from bottom of drawing sheet.

Explanation:?

SL.NO.	OBJECT	CONVENTIONAL SIGN	COLOUR
27.	JUNCLE		HEDGE GREEN
28.	ORCHARD		HEDGE GREEN
29.	CULTIVATED LAND		DRAINS PRUSSIAN BLUE CULTIVATION GREEN
30.	BARREN LAND		BLACK
31.	ROUGH PASTURE		BLACK
32.	MARSH OR SWAMP		BLACK
33.	SAND HILL		BLACK
34.	EMBANKMENT		BLACK
35.	CUTTING		BLACK
36.	FOOTH-PATH		BURNT UMBER
37.	VILLAGE CART-TRACK		BURNT UMBER
38.	UNMETALED ROAD		BURNT SIENNA
39.	METALLED ROAD		BURNT SIENNA
40.	RAILWAY SINGLE LINE	or	BLACK
41.	RAILWAY DOUBLE LINE		BLACK
42.	ROAD BRIDGE		BURNT SIENNA
43.	RAILWAY BRIDGE		BLACK
44.	ROAD & RAIL LEVEL CROSSING		RAIL- BLACK ROAD - BURNT SIENNA
45.	TELEPHONE OR TELEGRAPH LINE		BLACK
46.	ELECTRIC LINE		BLACK
47.	NORTH DIRECTION		BLACK
48.	DEMARCATED PROPERTY BOUNDARY
49.	UNDEMARCATED PROPERTY BOUNDARY
50.	CULVERT
51.	ELECTRIC LINE

Dimensioning relates to geometry of machine part/plot but not material, transparency, physical, mechanical, chemical properties of machine part/plot. Or than dimensions are placed near title block of drawing sheet if necessary.

The dimensioning of circle depends upon size or diameter of circle. If diameter of circle is considerably large, dimension can be given inside circle itself. It should be noted that dimension of circle should be given in view where its true shape is visible.

Arrowheads should ordinarily be drawn within dimensioned feature. But when re are fewer space arrowheads can also be kept outside and a dot may also be used to replace arrowhead and also if re is no space for dimension figure to be kept on dimension line figure may be written above extended portion of dimension line.

Extension lines should start immediately from outlines of views. There should be no gap between outlines and extension lines. Dimensions should not be given on outlines mselves and refore extension lines should be used.

In unidirectional system all dimensions are placed such that y can be read from bottom of drawing sheet. The dimension lines are broken near middle for inserting dimensions. This is used in mainly large drawings.

For figures having a value less than one, dimensions should be written as 0.5 or 0.3 as per value. There needs to be a zero in front of point if it is less than 1. Sometimes zero is omitted but this practice should not be encouraged.

The dimensions are arranged parallel to each or in horizontal dimensioning and in straight line for vertical dimensioning. There is a need for calculation for finding out some dimensions. The dimension figures can be read only from bottom.