[TYPO3] Attempting concatenation - syntax issue?

[John Kallies]

My extension templates aren't producing HTML to call my style sheets. 
I've included the syntax and a little context. I'm using Typo3 3.8.1. 
I've found a less elegant workaround to my problem below, but I would 
really like to know what I am doing wrong, if anyone is willing to show me.

There are 4 templates in play here...

- siteRoot - only includes basis templates, and a template for the next
   level (allowing different front page). Nothing else here.

- globalTS template - used by the siteRoot template. All the heavy
   lifting goes here (automaketemplate, tt_news pid, etc.)

- corporateStyle - defines the overall UI/brand of the site. Included by
   the siteRoot

- departmentStyle - ext. template on a child page (a couple levels in),
   defining department-level UI

The code in use...
----------------------------------------------------------------------------
# From the setup of the globalTS basis template. Trying to do a
# poor-man's concatenation in TypoScript

   page.headerData.700 = TEXT
   page.headerData.700 {
     10.value = <link rel="stylesheet" type="text/css" href="
     20.value = {$constants.stylesheet}
     30.value = " />
   }

[also did this...]

   page.headerData.700 = TEXT
   page.headerData.700.10.dataWrap = <link rel="stylesheet"
   type="text/css" href="{$constants.stylesheet}" />

# From the constants in the corporateStyle basis template

   constants.stylesheet =
   /fileadmin/templates/corporate/styles_corporate_main.css

# From the constants in the departmentStyle basis template

   constants.stylesheet =
   /fileadmin/templates/department1/styles_department1_main.css


----------------------------------------------------------------------------

Of course my TS doesn't line wrap like this message.

If I hard code a literal value in page.headerData.700, everything is 
fine. So there's something amiss in my constants or setup code.

For reasons discussed on this list, I don't want to use a 
page.stylesheet = fileadmin/yadda/yadda.css because I can't control or 
readily override the use of a given stylesheet (for IE hacks, et al.).

I think my template architecture is good. I'm guessing there's something 
screwy with my faux-concatenation syntax, but I've used this before and 
it worked fine. I would be very grateful for some insight.

Many thanks...
John Kallies