Arbitrary vertical space can be added using the vspace command.

vspace number [attributes];
vspace: label [attributes];

In the first form the vertical space is specified as a number in points. In the secod form, the height of the given label will be used. This command also has a specific attribute, called compressable, which specifies if the space should be ignored if compress is on. It defaults to no.

Horizontal spacing between the entities can be controlled either via the pos and relative entity attributes or can be made fully automatic by specifying hscale=auto;, see Entity Positioning and Chart Options.

The hspace command is useful in the latter case to force a certain horizontal distance between two (not necessarily neighbouring) entity. The space can be larger than the one specified with hspace if the layout requires so, but never smaller.

hspace entity-entity number [attributes];
hspace entity-entity: label [attributes];
hspace left comment number [attributes];
hspace right comment number [attributes];

The syntax is similar to that of the vspace command, both a number or a label can be used to specify the horizontal distance. Before the distance, the two entities need to be specified. Any one can be omitted, in this case the distance is proscribed between the edge of the chart and the entity^[36]. Two special versions of the hspace command exist to specify the spacing for the comments on the right and left sides.

The hspace command can be specified anywhere in the file with the same effect.

Currently Msc-generator can draw circles (ellipses), ellipses (three dots) and rectangles (optionally with text) or just plain text. We call these symbols.

symbol arc|rectangle|...|text marker-marker hpos1 hpos2 [attributes];

By specifying either arc, rectangle, ... or text after the symbol keyword one instructs Msc-generator to draw one circle/ellipsis, rectangle, ellipses or just text^[37], respectively.

The vertical position of the symbols can be specified two ways. Either they are in-line, which means they occupy space and the layout engine takes them into account when laying out entities above below. In this case symbols will be drawn at the vertical position where they are specified in the file, just like any other element (except verticals). To achieve in-line placement, just omit the markers (and the dash in-between) from the above syntax.

Otherwise it is possible to specify the vertical position where the symbol should appear. This can be done via markers, similar as for verticals, see Verticals. In this case however, the layout engine will ignore the symbol and it will be drawn either behind or in front of other elements.

The vertical size of the object can be specified two ways. Either you specify two markers (as above), in which case the symbol will vertically span from one to the other; or you omit one of the markers, in which case the ysize attribute specifies the height (in points)^[38]. If the dash is in front of the marker, the bottom of the symbol will be aligned with the marker. If the dash is after the marker, then the marker designates the top of the symbol.

In the example below we see three rectangles. One stretches between two markers, the second is bottom aligned, while the third is top aligned.

The horizontal position of the symbol is specified via one or two horizontal position specifiers. They specify the horzontal position of either the left or right edge of the symbol or of its center. This is governed by the first keyword

left|center|right at entity-entity [number]
left|center|right at entity--
left|center|right at entity-
left|center|right at entity [number]
left|center|right at entity+
left|center|right at entity++

Then, after the at keyword one specifies either one entity with additional modifiers or two entities. In the former case the horizontal position will be at the middle of the entity’s line or somewhat left or right of it depending on the modifiers. In the latter the horizontal position will be between the two entities. Two of the forms can also take a number, which is interpreted as pixels and will shift the position to the right for positive values and to the left for negative values.

If you specify two such horizontal position specifiers one after the other, they describe both the placement of the symbol and its width. If you specify one, the width of the symbol can be specified using the xsize attribute^[39]. This may sound a bit complicated, so here is an example with 5 in-line symbols.

Whether the symbol is drawn behind or in front of other elements can be controlled by the ‘draw_time’ attribute. It can take the following values.

Note that from v3.3.4 any element can specify the draw_time attribute. It will not impact thet layout only the drawing order (what is called the z-order).

As you can see the first (leftmost) rectangle was drawn below the entity lines, the second (middle) one between the entity lines and the arrows, while the last (rightmost) one was drawn on top of the arrows.

Finally we show a few examples of how symbols may be used.

Sometimes one just wants to add some text to the diagram and in this case the symbol text syntax may be a bit heavy and difficult to do. As an easier way to do that Msc-generator offers the text at command.

text at pos [attributes]: label;

This draws just text (you must specify a label) at the vertical position the command is written. You can use simple horizontal position specifiers, like below to place the text centered in-between two entities; left of an entity, centered around an entity or right of an entity. You can optionally specify a number, which will be interpreted as a pixel offset to the right (negative value to the left.)

entity-entity [number]
entity-- [number]
entity- [number]
entity [number]
entity+ [number]
entity++ [number]

You can influence the default appearance via the text built-in style.