Blocks

A block is a collection of associated drawing objects processed as a whole entity. A block can be created of any number of objects and inserted in a drawing any number of times.

It is convenient to use blocks to create drawing elements for multiple use, thus accelerating and simplifying the drawing process.

Blocks can be used to create user libraries of frequently used parts and details.

Relating all references of a block to the same block description in the drawing database allows you to decrease the file size, as with every new insertion of a block, only information about the insertion place, scale factors and rotation angle is added to the information available.

A block creation implies its definition (description), which is stored in the block table of a document and is not displayed in a drawing. A block definition can contain links to other (nested) blocks. The only restriction to nesting blocks is that they cannot be inserted to themselves.

A block insertion in a drawing is called a block reference (block instance).

Any block description can have multiple references or not have any. When modifying a block description (or redefining a block), all its references are changed automatically.

An existing block (definition) can be changed by redefining it. After modifying a block definition, all references of this block in a document change automatically.

When a block is created, objects are placed in the block together with their current property values that cannot be changed without a block redefining. For example, if a block was created of red segments, it will be not possible to change segments color after the block is created. Therefore, it is required to take thought of the block behavior at its insertion in advance, i.e. at the stage of its creation.

So that:

·         a block properties are defined by properties of a layer it will be placed on, with assignment of color, linetype and lineweight of this layer to all objects included in the block, it is necessary to create all block objects on the 0 layer with assignment of color, linetype and lineweight By layer.

·         color, linetype and lineweight of block objects are defined at placing it in a drawing, it is necessary to assign color, linetype and lineweight By layer to block objects when creating. In other words, block objects in this case inherit current values of color, linetype and lineweight. If current properties are not specified explicitly in a drawing, block objects will inherit properties of the current layer.

·         block objects retain their original properties, i.e. always have certain color, linetype and lineweight, the respective properties should be explicitly specified before the objects are included in the block definition. In other words, when creating block objects in this case you should not use settings of color, linetype and lineweight By layer or By block.

When being created, a block can be attended with attributes, i.e. explanatory text, which is acceptable to change in the process of inserting the block in the drawing and which can be displayed on the screen or stay invisible (hidden) and is not printed out.

There are several ways to create and use blocks:

·         It is possible to group objects and save them as a block in the current drawing (menu Draw – Block > Create);

·         It is possible to save a block in a separate file to use it in other drawings by specifying WBLOCK command in the command line;

·         It is possible to insert a drawing with available blocks as a reference to any other drawing (menu Insert – Block, Open button in the Insert block dialog box);

·         It is possible to create a file with a set of frequently used blocks to use it as a library.