There are times when a rare accented character is needed, but it is not readily available in the selected font. While it is possible to build such a character by using a combination of BC (backup center) and UP/DN mark-up commands in MECCA, it is nonetheless inconvenient, plus the resulting "character" is not subject to font size change. A new immediate command, CBC (ComBined Character; although the BC part also hints its automatic centering operation, much like the BC command), has been added. It lets the user set a base character, then a sequence of "mark characters" (those stand-alone accent glyphs) to be placed above or below the base character, while keeping all those characters centered. The basic command syntax is: \cbc base,gap-direction,mark^ where: "base" is the base character. "gap-direction" specifies: The vertical gap in EM units (for MECCA, there are 100 units per EM) between the characters' bounding boxes. The direction: "above" or "below", indicated by a single character 'a' or 'b'. "mark" is the character to be placed above or below the base character. As an example, there is no "o-cedilla" in a standard font, but using CBC, and the \013 special character code for cedilla, here's "o-cedilla": \cbc o,b,\013^ where o is the base character, the 'b' says "no gap, and place below", and the mark is cedilla (which is to be placed below o). Another example: \cbc o,6.6a,-^ Makes "o with hyphen above, having a gap of 6.6 units between o and hyphen". The default gap for above or below is always zero, such that the bounding boxes of the characters touch. This is because there is no standard gap size in typeface design, and gaps between base and accent glyphs can vary between 6.6 and 10 EM units (as observed in existing font files), with 8.33 being suggested by Unicode.org (1/12 EM), so providing one default gap value is impractical for all typefaces. Also, if CBC command processor were to maintain a default value, customers will have to memorize that, and then modify the default gap. Given that it is rare when customers face the need to build such combined characters, letting customers specify all gap values whenever they need to, is a better answer. The gap value can be negative: look at the "o-cedilla" example, since no gap was specified, the o and cedilla bounding boxes just touch, and the result don't look quite right. Normally cedilla is placed below the base character but with some overlap, so you can do this: \cbc o,-2b,\013^ This causes the cedilla and o bounding boxes to overlap by 2 EM units, and the combination now looks much better. The vertical gap value, given before either 'a' or 'b', is positive to "loosen or spread" the characters, negative to "tighten or contract" the characters, vertically. You can place both "above" and "below" parts in one CBC command. The above two examples may be combined into one "o-cedilla with hyphen above": \cbc o,6.6a,-,-2b,\013^ Or, you can create an "o with hyphen above and below, plus a cedilla tail": \cbc o,6.6a,-,6.6b,-,-2b,\013^ Note that there are two "below" characters now: first the hyphen, 6.6 units below o, then the cedilla, overlapping 2 units with the hyphen (not the o). This last example illustrates two things: 1. The gap is always the distance between the "current bounding box", and the bounding box of "the next character". The base character defines the initial bounding box. 2. You can use any number of above/below characters in one CBC command, and there is no preset requirement as to the order of above or below placement. The last example could be re-written with "below parts first": \cbc o,6.6b,-,-2b,\013,6.6a,-^ and will produce the same result (of course, you can also sandwich the one "above hyphen" between the two "below" parts, the result will again, be the same). Sharp eyed customers may have noticed: when you use a \NNN character code in a CBC sequence, you do not terminate it with a caret. This is the only condition where a special character code need not (indeed, must not) be terminated with a caret -- CBC itself is an immediate command, and immediate commands do not nest in MECCA. One final syntax note, as we examine the "o-cedilla" more: \cbc o,-2b,\013^ If the font is in italic, MECCA will recognize that fact, and center the cedilla accordingly (pulling it to the left a little bit, per the italic angle). However, that amount may not be enough -- curious customers can compare with the "c-cedilla" in Helvetica Italic (ge/i), \403^, which does exist in the font, to see the difference -- and you may want to do a little horizontal adjustment yourself. Here is how: Give any horizontal adjustment (in units of EM), AFTER the 'a' or 'b' directional indicator. Negative value pulls to the left, and positive value pushes toward the right. For example: \cbc o,-2b-2,\013^ will not only overlap cedilla on the bottom by 2 units, but also move the cedilla left by 2 units (after centering and any italic adjustment). Horizontal adjustment like this does not "carry over": if you place another character below the cedilla, that character will not retain the -2 horizontal adjustment applied to the cedilla. Caution: 1. CBC is meant to create a combined character as if that character was in the font. Therefore, any font, style, color etc. properties you want, must be set before using CBC. Inside the CBC command, there can be no other immediate command. 2. The base character is always used for kerning purpose. 3. The "width of a CBC character" is the widest of all characters in the sequence, not the "combined total width of all characters". 4. Depending on font used and surrounding characters, an HSA command may need to follow CBC in order to tighten letter spacing. 5. Color or density graduation over a CBC character is not well supported. 6. CBC character is not supported for spelling check, i.e. it is handled as a normal immediate command and skipped during spelling check, it is not treated as "one character" (that may reside in a word).