Entities are placed on the chart from left to right in the order of definition. This can be influenced by the pos and relative attributes.

Specifying pos will place the entity left or right from its default location. E.g., specifying pos=-0.25 for entity B makes B to be 25% closer to its left neighbour. Thus pos shall be specified in terms of the unit distance between entities. (Which is 130 points - a historic value kept for backwards compatibility.)

The next entity C, however, will always be from a unit distance from the entity defined just before it, so in order to specify a 25% larger space, on the right side of entity B, one needs to specify pos=0.25 for C.

The attribute relative can be used to specify the base of the pos attribute. Take the following input, for example. In this case C will be placed halfway between A and B.

Note that specifying the hscale=auto chart option makes entity positining automatic. This setting overrides pos values with the exception that it maintains the order of the entities that can be influenced by setting their pos attribute. See Chart Options. In most cases it is simpler to use hscale=auto, you need pos only to fine-tune a chart, if automatic layout is not doing a good job.

A group entity can contain other entities. Groups can be nested arbitrary deep. To specify a group entity, use curly braces after an entity definition (but before the colon or comma). Between the braces you can list entity definitions, style/color definitions or chart options^[17]. The curly braces open a new scope, so any style or color definition or chart option takes its effect only within the group of entities between the curly braces. See Scoping for more information.

Any entity you specify in the group must be a newly defined entity. It is not possible to place already defined entities into a group. Similar, an already defined entity cannot be made a group entity later by adding entities to it. Nor can a group be later extended with additional entities.

The position of a group entity is derived from its members so the ‘pos’ and ‘relative’ attributes cannot be used.

Group entities can be collapsed, by setting the ‘collapsed’ attribute to yes (or via the GUI on Windows). A collapsed group entity does not show its member entities, but is displayed as a non-grouped entity. Arrows and boxes in the chart are modified (or even removed) to reflect the collapse. If the ‘indicator’ attribute of the entity is set to yes, a small indicator is shown both inside the collapsed entity and for each arrow or box removed.

The following entity attributes can only be set at the definition of the entity.

The following attributes can be changed at any location and have their effect downwards from that location.

It is not required to explicitly define an entity before it is used. Just typing the arrow definition a->b; will automatically define entities ‘a’ and ‘b’ if not yet defined. This behaviour can be disabled by specifying the --pedantic command-line option or specifying pedantic=yes chart option. See Chart Options. Disabling implicit definition is useful to generate warnings for mis-typed entity names^[18].

Implicitly defined entities always appear at the very top of the chart. If you want an entity to appear only later, define it explicitly.

By default, when an entity is defined, its heading is drawn at that location. If the entity name is preceeded by the hide keyword or the show=no attribute is specified at the entity definition then the entity heading is not drawn at the location of the definition. It is drawn later, if/when the entity is turned on by using show followed by the entity name or by setting show=yes. Note that multiple entities can be listed after both show and hide. It is also possible to specify other attributes for entities after these keywords.

Mentioning an entity after its definition either preceeded by show or with show=yes will cause an entity heading to be drawn into the chart even if the entity is already shown. This can be useful for long charts, see Defining Entities for examples.

You can display all of the entity headings using the heading; command, as well. This command displays an entity heading for all (currently showing) entities. This may be useful after a newpage; command, see Commands. However, the best practice is to use ‘newpage [auto_heading=yes];’ instead, since it only shows the heading when the chart is viewed per-page (which is the same for page breaks inserted by automatic pagination).

The shape of an entity heading can be altered from the default box-like appearance to something custom using the shape attribute. Its value is a string, the name of the shape. The actual appearance of shapes is defined in separate files. Msc-generator comes with a few default shapes (their name all start with def.), but you can define your own shapes or add third-party Defining Shapes. See Defining Shapes for more.

For some shapes, the label of the entity is written inside the shape, for some it is written below. This is decided by the author of the shape. If the label is written inside, it is scaled to fit. You can influence the size of the shape via the shape.size attribute, which takes the values tiny, small, normal, big or huge with small as default.

Note that the above two attributes can be set in the entity and the entitygroup_collapsed style, which will influence all entities in a chart at once.